Polyimide metal clad laminate

ABSTRACT

The present disclosure is directed to a polyimide metal clad laminate. The metal clad laminate has a metal foil and a polyimide layer. The polyimide layer having a polyimide derived from 100 mole % 3,3′,4,4′-biphenyl tetracarboxylic dianhydride, 20 to 90 mole % 2,2′-bis(trifluoromethyl)benzidine, and 10 to 80 mole % 4,4′-oxydianiline. The polyimide metal clad laminate does not have an adhesive layer between the metal foil and the polyimide layer.

FIELD OF DISCLOSURE

This disclosure relates generally to a polyimide metal clad laminate.

BACKGROUND OF THE DISCLOSURE

Metal clad laminates for circuit board construction are constructed bylaminating a polyimide film to a metal foil with an adhesive layer inbetween. The adhesive layer may consist of conventional adhesives(acrylates, epoxides, polyamides, phenolic resins, etc.) where theadhesive is cured during the metal foil lamination. However, theseconventional adhesives do not usually possess the high temperature heatstability of the base polyimide dielectric, and the strength of theadhesive bonds in the multiplayer laminate structure deterioratesrapidly when subjected to elevated temperatures. These adhesives alsoshow high electric loss in high speed circuit layers due to the highloss tangent of these adhesives.

As electronic packaging becomes more sophisticated and the desire forthinner, smaller, light weight, flexible, electronic components with lowCTE, low moisture absorption, high temperature heat stability and highmodulus have necessitated the elimination of the adhesive layer.

One means to an adhesiveless laminate is to coat a high moduluspolyimide film core layer with a thin layer of polyamic acid precursorsolution on both sides, dry this layer, and finally imidize the appliedcoating to create a thermoplastic polyimide. Copper foil is thenlaminated with heat and pressure to create a double sided copper cladlaminate.

A polyimide precursor can also be coated directly onto copper foil andthen cured to create a polyimide film with copper foil on one side. Thisis a common method of making adhesiveless copper clad films but cancreate polyimide clads with copper on just one side. Another method ofmaking adhesiveless polyimide copper clad laminates is to start with astandard rigid polyimide base film. A thin metal layer is deposited,typically by sputtering or vapor deposition to improve adhesion betweenthe metal and the polyimide. Then the copper is electroplated up to therequired thickness to create a double sided copper clad laminate.

Each of these suffers from one or more of the following disadvantages:requisite additional steps as opposed to lamination of a metal foil(s)to polyimide film, inferior adhesion of the metal foil to the polyimidewhen an adhesive is used, multiple layers of polyimide add to overallthe thickness of the construction.

For the forgoing reasons, a need exists for polyimide films that can bedirectly laminated/adhered to metal foils without using an adhesive toproviding thinner, flexible electronic components with low CTE, lowmoisture absorption, high temperature heat stability while maintaininggood mechanical and electrical properties.

DETAILED DESCRIPTION Definitions

As used herein, the terms “comprises,” “comprising,” “includes,”“including,” “has,” “having” or any other variation thereof, areintended to cover a non-exclusive inclusion. For example, a method,process, article, or apparatus that comprises a list of elements is notnecessarily limited only to those elements but may include otherelements not expressly listed or inherent to such method, process,article, or apparatus. Further, unless expressly stated to the contrary,“or” refers to an inclusive or and not to an exclusive or. For example,a condition A or B is satisfied by any one of the following: A is true(or present) and B is false (or not present), A is false (or notpresent) and B is true (or present), and both A and B are true (orpresent).

Also, use of the “a” or “an” are employed to describe elements andcomponents of the invention. This is done merely for convenience and togive a general sense of the invention. This description should be readto include one or at least one and the singular also includes the pluralunless it is obvious that it is meant otherwise.

The term “dianhydride” as used herein is intended to include precursors,derivatives or analogs thereof, which may not technically be adianhydride but would nevertheless react with a diamine to form apolyamic acid which could in turn be converted into a polyimide.

The term “diamine” as used herein is intended to include precursors,derivatives or analogs thereof, which may not technically be a diaminebut would nevertheless react with a dianhydride to form a polyamic acidwhich could in turn be converted into a polyimide.

The term “polyamic acid” as used herein is intended to include anypolyimide precursor material derived from a combination of dianhydrideand diamine and capable of conversion to a polyimide.

The term “film” as used herein is intended to mean a free-standing filmor a (self-supporting or non-self-supporting) coating. The term “film”is used interchangeably with the term “layer”.

The term “chemical conversion” or “chemically converted” as used hereindenotes the use of a catalyst (accelerator) or dehydrating agent (orboth) to convert the polyamic acid to polyimide and is intended toinclude a partially chemically converted polyimide which is then driedat elevated temperatures to a solids level greater than 98%.

The term “metal” as used herein is intended to include elemental metalsand metal alloys.

The term “direct contact” as used herein is intended to mean that layersare in contact with one another at their interface and an interveninglayer, such as an adhesive layer, is not present.

When an amount, concentration, or other value or parameter is given aseither a range, preferred range or a list of upper preferable values andlower preferable values, this is to be understood as specificallydisclosing all ranges formed from any pair of any upper range limit orpreferred value and any lower range limit or preferred value, regardlessof whether ranges are separately disclosed. Where a range of numericalvalues is recited herein, unless otherwise stated, the range is intendedto include the endpoints thereof, and all integers and fractions withinthe range.

Numerical values are to be understood to have the precision of thenumber of significant figures provided. For example, the number 1 shallbe understood to encompass a range from 0.5 to 1.4, whereas the number1.0 shall be understood to encompass a range from 0.95 to 1.04,including the end points of the stated ranges. It is not intended thatthe scope of the invention be limited to the specific values recitedwhen defining a range.

In describing certain polymers it should be understood that sometimesapplicants are referring to the polymers by the monomers used to makethem or the amounts of the monomers used to make them. While such adescription may not include the specific nomenclature used to describethe final polymer or may not contain product-by-process terminology, anysuch reference to monomers and amounts should be interpreted to meanthat the polymer is made from those monomers, unless the contextindicates or implies otherwise.

The materials, methods, and examples herein are illustrative only and,except as specifically stated, are not intended to be limiting. Althoughmethods and materials similar or equivalent to those described hereincan be used, suitable methods and materials are described herein.

The present disclosure is directed to a thermoset polyimide film thatcan be directly adhered to metal and have good peel strength without theneed for an additional adhesive layer. Good peel strength, for a metalclad laminate for the purpose of this disclosure, is at least 1 N/mm.Good peel strength for a coverlay or a bondply is 0.7 to 2 N/mm.

In some embodiments, a polyimide film (polyimide layer or polyimidecoverlay or polyimide bondply or electrically insulating layer)comprises a polyimide derived from 100 mole % 3,3′,4,4′-biphenyltetracarboxylic dianhydride, 20 to 90 mole %2,2′-bis(trifluoromethyl)benzidine, and 10 to 80 mole %4,4′-oxydianiline and is capable of directly adhering to metal and otherpolymers at lamination temperatures from 300 to 380° C.

In some embodiments, a polyimide film (polyimide layer or polyimidecoverlay or polyimide bondply or electrically insulating layer)comprises a polyimide derived from 100 mole % 3,3′,4,4′-biphenyltetracarboxylic dianhydride, 20 to 90 mole %2,2′-bis(trifluoromethyl)benzidine, and 10 to 80 mole %4,4′-oxydianiline and is capable of directly adhering to metal and otherpolymers at lamination temperatures from 330 to 380° C.

In some embodiments, a polyimide film (polyimide layer or polyimidecoverlay or polyimide bondply or electrically insulating layer)comprises a polyimide derived from 100 mole % 3,3′,4,4′-biphenyltetracarboxylic dianhydride, 40 to 90 mole %2,2′-bis(trifluoromethyl)benzidine, and 10 to 60 mole %4,4′-oxydianiline and is capable of directly adhering to metal and otherpolymers at lamination temperatures from 320 to 380° C.

In some embodiments, a polyimide film (polyimide layer or polyimidecoverlay or polyimide bondply or electrically insulating layer)comprises a polyimide derived from 100 mole % 3,3′,4,4′-biphenyltetracarboxylic dianhydride, 20 to 30 mole %2,2′-bis(trifluoromethyl)benzidine, and 70 to 80 mole %4,4′-oxydianiline and is capable of directly adhering to metal and otherpolymers at lamination temperatures from 330 to 380° C.

In some embodiments, a polyimide film (polyimide layer or polyimidecoverlay or polyimide bondply or electrically insulating layer)comprises a polyimide derived from 100 mole % 3,3′,4,4′-biphenyltetracarboxylic dianhydride, 20 to 90 mole %2,2′-bis(trifluoromethyl)benzidine, and 10 to 80 mole %4,4′-oxydianiline and is capable of directly adhering to metal and otherpolymers at lamination temperatures of at least 300, 320, 330 or 350° C.

In some embodiments, a polyimide film (polyimide layer or polyimidecoverlay or polyimide bondply or electrically insulating layer)comprises a polyimide derived from 100 mole % 3,3′,4,4′-biphenyltetracarboxylic dianhydride, 40 to 90 mole %2,2′-bis(trifluoromethyl)benzidine, and 10 to 80 mole %4,4′-oxydianiline is capable of directly adhering to metal and otherpolymers at lamination temperatures of at least 300, 320, 330 or 350° C.

A polyimide derived from 100 mole % 3,3′,4,4′-biphenyl tetracarboxylicdianhydride, 100 mole % 2,2′-bis(trifluoromethyl)benzidine, is capableof directly adhering to metal and other polymers at laminationtemperatures from 380 to 404° C.

Thus the polyimides of the present disclosure are useful for anyapplication where direct adherence of a polyimide to metal is beneficialand thin, flexible electronic components with low CTE, low moistureabsorption are desired such as, but not limited to, metal cladlaminates, coverlays and bondplys.

Metal Clad Laminate

In some embodiments, the polyimide metal clad laminate of the presentdisclosure comprises a metal foil and a polyimide layer. The polyimidelayer having a first side and a second side, the first side in directcontact with the metal foil, the polyimide layer comprising: a polyimidederived from 100 mole % 3,3′,4,4′-biphenyl tetracarboxylic dianhydride,20 to 90 mole % 2,2′-bis(trifluoromethyl)benzidine, and 10 to 80 mole %4,4′-oxydianiline; wherein the polyimide metal clad laminate does nothave an adhesive layer between the metal foil and the polyimide layer.The polyimide metal clad laminate has a peel strength of from 1 to 3.3N/mm, as measured in accordance with IPC-TM-650-2.4.9d, when the metalfoil and the polyimide layer are laminated together at a laminationtemperature from 320 to 380° C. and a pressure from 150 psi (10.55Kg/cm) to 400 psi (28.13 Kg/cm).

In one embodiment, the polyimide metal clad laminate of the presentdisclosure comprises a metal foil and a polyimide layer. The polyimidelayer having a first side and a second side, the first side in directcontact with the metal foil, the polyimide layer comprising: a polyimidederived from 100 mole % 3,3′,4,4′-biphenyl tetracarboxylic dianhydride,40 to 90 mole % 2,2′-bis(trifluoromethyl)benzidine, and 10 to 60 mole %4,4′-oxydianiline; wherein the polyimide metal clad laminate does nothave an adhesive layer between the metal foil and the polyimide layer.The polyimide metal clad laminate has a peel strength of from 1 to 3N/mm, as measured in accordance with IPC-TM-650-2.4.9d, when the metalfoil and the polyimide layer are laminated together at a laminationtemperature from 320 to 380° C. and a pressure from 150 psi (10.55Kg/cm) to 400 psi (28.13 Kg/cm).

In another embodiment, the polyimide metal clad laminate of the presentdisclosure comprises a metal foil and a polyimide layer. The polyimidelayer having a first side and a second side, the first side in directcontact with the metal foil, the polyimide layer comprising: a polyimidederived from 100 mole % 3,3′,4,4′-biphenyl tetracarboxylic dianhydride,20 to 30 mole % 2,2′-bis(trifluoromethyl)benzidine, and 70 to 80 mole %4,4′-oxydianiline; wherein the polyimide metal clad laminate does nothave an adhesive layer between the metal foil and the polyimide layer.The polyimide metal clad laminate has a peel strength of from 1 to 3.2N/mm, as measured in accordance with IPC-TM-650-2.4.9d, when the metalfoil and the polyimide layer are laminated together at a laminationtemperature from 330 to 350° C. and a pressure from 150 psi (10.55Kg/cm) to 400 psi (28.13 Kg/cm).

In another embodiment, polyimide metal clad laminate comprises a metalfoil and a polyimide layer having a first side and a second side, thefirst side in direct contact with the metal foil, the polyimide layercomprising: a polyimide derived from 100 mole % 3,3′,4,4′-biphenyltetracarboxylic dianhydride, and 100 mole %2,2′-bis(trifluoromethyl)benzidine; wherein the polyimide metal cladlaminate does not have an adhesive layer between the metal foil and thepolyimide layer, and wherein the polyimide metal clad laminate has apeel strength of from 1 to 3 N/mm, as measured in accordance withIPC-TM-650-2.4.9d, when the metal foil and the polyimide layer arelaminated together at a lamination temperature from 380 to 400° C. and apressure from 150 psi (10.55 Kg/cm) to 400 psi (28.13 Kg/cm).

In some embodiments, the polyimide metal clad laminate of the presentdisclosure comprises a metal foil and a polyimide layer. The polyimidelayer having a first side and a second side, the first side in directcontact with the metal foil, the polyimide layer comprising: a polyimidederived from 100 mole % 3,3′,4,4′-biphenyl tetracarboxylic dianhydride,20 to 90 mole % 2,2′-bis(trifluoromethyl)benzidine, and 10 to 80 mole %4,4′-oxydianiline; wherein the polyimide metal clad laminate does nothave an adhesive layer between the metal foil and the polyimide layer.The polyimide metal clad laminate has a peel strength of at least 1N/mm, as measured in accordance with IPC-TM-650-2.4.9d, when the metalfoil and the polyimide layer are laminated together at a laminationtemperature of at least 320° C. and a pressure from 150 psi (10.55Kg/cm) to 400 psi (28.13 Kg/cm).

In some embodiments, the polyimide is derived from 100 mole %3.3′,4,4′-biphenyl tetracarboxylic dianhydride, between and includingany two of the following: 20, 30, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85and 90 mole % 2,2′-bis(trifluoromethyl)benzidine, and between andincluding any two of the following: 10, 15, 20, 25, 30, 35, 40, 45, 50,55, 60, 70 and 80 mole % 4,4′-oxydianiline.

In some embodiments, the polyimide metal clad further comprises a secondmetal foil in direct contact with the second side of the polyimide layerand wherein the polyimide metal clad laminate does not have an adhesivelayer between the second metal foil and the polyimide layer.

In some embodiments, the polyimide metal clad laminate comprises:

-   -   a. a metal foil;    -   b. a polyimide layer having a first side and a second side, the        first side in direct contact with the metal foil, the polyimide        layer comprising: a polyimide derived from 100 mole %        3,3′,4,4′-biphenyl tetracarboxylic dianhydride, 20 to 90 mole %        2,2′-bis(trifluoromethyl)benzidine, and 10 to 80 mole %        4,4′-oxydianiline; and    -   c. a second metal foil; and        the polyimide metal clad laminate does not have an adhesive        layer between the metal foil and the polyimide layer and the        polyimide metal clad laminate has a peel strength of from 1 to 3        N/mm, as measured in accordance with IPC-TM-650-2.4.9d, when the        metal foil and the polyimide layer are laminated together at a        temperature from 320 to 380° C. and a pressure from 150 psi        (10.55 Kg/cm) to 400 psi (28.13 Kg/cm).

In some embodiments, the polyimide metal clad laminate comprises:

-   -   a. a metal foil;    -   b. a polyimide layer having a first side and a second side, the        first side in direct contact with the metal foil, the polyimide        layer comprising: a polyimide derived from 100 mole %        3,3′,4,4′-biphenyl tetracarboxylic dianhydride, and 100 mole %        2,2′-bis(trifluoromethyl)benzidine; and    -   c. a second metal foil.        The polyimide metal clad laminate does not have an adhesive        layer between the metal foil and the polyimide layer and does        not have an adhesive layer between the second metal foil and the        polyimide layer and the polyimide metal clad laminate has a peel        strength of from 1 to 3 N/mm, as measured in accordance with        IPC-TM-650-2.4.9d, when the metal foil and the polyimide layer        are laminated together at a temperature from 320 to 380° C. and        a pressure from 150 psi (10.55 Kg/cm) to 400 psi (28.13 Kg/cm).

It is surprising the polyimides of the present disclosure have good peelstrength with metals, and imaged metal having exposed polymer areaswhere the metal was removed, without the need for an adhesive whenlaminated at temperatures from 320 to 380° C., and in some embodiments,laminated at temperatures from 380 to 400° C., and maintain a goodbalance of mechanical and electrical properties as well as low CTE. Notall low Tg polyimides have good peel strength, balance of properties andlow CTE.

Desirable electrical properties and mechanical properties will depend onthe desired end use that the material will be used for. Ordinary skilland experimentation may be necessary in fine tuning properties fordesired end use. Generally, good MD tensile modulus is greater than 2.75GPa, MD tensile strength is greater than 125 MPa, MD elongation isgreater than 25%, water uptake less than 1.5%, dielectric constant at100 Hz less than 3.5 and loss tangent below 0.006.

Another advantage of a single layer polyimide film having the ability todirectly adhere to metal foil, is film thickness uniformity can be moreeasily controlled for thicknesses less than 25 microns via a single slotcasting die than a multilayer casted film which relies on asophisticated layer combining system. All polyimide copper cladlaminates can be made with 3 layers; a rigid thermoset polyimide coreand thin thermoplastic polyimide coatings on both sides of the polyimidecore. However, it is difficult to control the thickness of the thincoatings, plus is requires much more complicated manufacturing methodsto make 3 layer film.

Another advantage of a single layer of polyimide film of the presentdisclosure is that it produces the properties expected of copper cladlaminate with a rigid polyimide core and also produces adhesion tocopper similar to a thermoplastic polyimide. Good adhesion to copperfoil could be achieved with an all thermoplastic polyimide film.However, the all thermoplastic films would have large CTE values (>50)that are unacceptable for metal clad laminates. Also the dimensionalstability is poor.

Another advantage is that thinner polyimide films can be made allowingfor higher thermal conductivity while maintaining electrical properties.

In some embodiments the polyimide layer (of the polyimide metal cladlaminate) is from, between and including any two of the following: 2, 5,10, 15, 20, 26, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95,100 and 105 microns thick. In some embodiments, the polyimide layer isfrom 2 to 26 micron thick. In some embodiments, the polyimide layer isfrom 27 to 105 micron thick.

Metal Foil—Metal Clad Laminate

In some embodiments, the metal foil is elemental metal. In someembodiments, the metal foil is a metal alloy. In some embodiments, themetal foil is copper. In some embodiments, the metal alloy comprises 50to 72 weight % nickel. In another embodiment, the metal alloy comprises50 to 72% weight % nickel an 14 to 24 weight % Chromium. In someembodiments, the metal foil is aluminum.

In some embodiments, the polyimide metal clad laminate further comprisesa second metal foil in direct contact with the second side of thepolyimide layer and wherein the polyimide metal clad laminate does nothave an adhesive layer between the second metal foil and the polyimidelayer.

In some embodiments, the second metal foil is elemental metal. In someembodiments, the second metal foil is a metal alloy. In someembodiments, the second metal foil is copper. In some embodiments, themetal alloy comprises 50 to 72 weight % nickel. In another embodiment,the metal alloy comprises 50 to 72% weight % nickel an 14 to 24 weight %Chromium. In some embodiments, the metal foil is aluminum.

In some embodiments, the metal foil is from 5 to 72 microns thick. Insome embodiments, the metal foil is between and including any two of thefollowing: 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70 and 72microns thick. In some embodiments, the metal foil is surface treated toimprove adhesion to electrically insulating layers.

In some embodiments, the second metal foil is from 5 to 72 micronsthick. In some embodiments, the second metal foil is between andincluding any two of the following: 5, 10, 15, 20, 25, 30, 35, 40, 45,50, 55, 60, 65, 70 and 72 microns thick. In some embodiments, the secondmetal foil is surface treated to improve adhesion to electricallyinsulating layers.

In some embodiments, the polyimide layer comprises from 1 to 55 weightpercent of a thermally conductive filler, dielectric fillers or mixturesthereof. In some embodiments, the polyimide layer comprises between andincluding any two of the following: 1, 5, 10, 20, 25, 30, 35, 40, 45, 50and 55 weight percent of a thermally conductive filler, dielectricfillers or mixtures thereof. In some embodiments the thermallyconductive filler, dielectric fillers or mixtures thereof are milled toobtain desired filler size and/or break up any agglomerates that mayhave formed.

The polyimide of the present disclosure can be made by any known thermalconversion or chemical conversion method for making polyimide films orfilled polyimide films. In some embodiments, it is desirable to usechemical conversion due to the advantages chemical conversion overthermal conversion such as but not limited to, lower CTE and films arematte on both sides even when cast on to a smooth surface.

In some embodiments, the polyimide layer can be a free standing filmthat is then directly adhered to metal foil, on one or both sides, usingnip roll lamination or vacuum press to form a metal clad laminate. Thenip roll or vacuum press must be capable of reaching the requiredtemperature and pressure.

In some embodiments, a polyamic acid can be cast on to metal foil andcured. This process can produce very thin electrically insulating layers(dielectric layers). And optionally another metal foil can be adhered tothe other side of the polyimide layer using a nip roll process or vacuumpress, capable of reaching the required temperature and pressure.

In some embodiment, the polyimide film can be a free standing film thatis then directly adhered to metal foil, on one or both sides, using niproll lamination or vacuum press to form a metal clad laminate.

In some embodiments a polyimide derived from 100 mole %3,3′,4,4′-biphenyl tetracarboxylic dianhydride, 40 to 90 mole %2,2′-bis(trifluoromethyl)benzidine, and 10 to 60 mole %4,4′-oxydianiline is used as a coverlay. In such embodiments, thepolyimide is directly adhered to copper and typically another polyimidelayer which is exposed after the copper has been imaged to formcircuitry.

Circuit Board—Coverlay

One embodiment of the present disclosure is a polyimide coverlay for acircuit board. In such an embodiment, the circuit board, comprises:

-   -   a. a first electrically insulating layer having a first side and        a second side;    -   b. a first imaged metal layer;    -   c. a first polyimide coverlay derived from 100 mole %        3,3′,4,4′-biphenyl tetracarboxylic dianhydride, 20 to 90 mole %        2,2′-bis(trifluoromethyl)benzidine, and 10 to 80 mole %        4,4′-oxydianiline and in direct contact with the first imaged        metal layer and exposed areas of the first side of the first        electrically insulating layer. An adhesive layer is not present        between the first imaged metal layer and the first polyimide        coverlay. In some embodiments, the first polyimide coverlay has        a peel strength from 0.7 to 2 N/mm, as measured in accordance        with IPC-TM-650-2.4.9d, when the first polyimide coverlay is        laminated to the first imaged metal layer and exposed areas of        the first side of the first electrically insulating layer at a        lamination temperature from 300 to 380° C. and a pressure from 1        50 psi (10.55 Kg/cm) to 400 psi (28.13 Kg/cm). The first        electrically insulating layer is any electrically insulating        material that can withstand the lamination temperature from 300        to 380° C.

In another embodiment, the first polyimide coverlay has a peel strengthfrom 1 to 2 N/mm, as measured in accordance with IPC-TM-650-2.4.9d, whenthe first polyimide coverlay is laminated to the first imaged metallayer and exposed areas of the first side of the first electricallyinsulating layer at a lamination temperature from 320 to 380° C. and apressure from 150 psi (10.55 Kg/cm) to 400 psi (28.13 Kg/cm). The firstelectrically insulating layer is any electrically insulating materialthat can withstand the lamination temperature from 320 to 380° C.

Another embodiment of the present disclosure is a polyimide coverlay fora circuit board. In such an embodiment, the circuit board, comprises:

-   -   a. a first electrically insulating layer having a first side and        a second side;    -   b. a first imaged metal layer;    -   c. a first polyimide coverlay derived from 100 mole %        3,3′,4,4′-biphenyl tetracarboxylic dianhydride, 40 to 90 mole %        2,2′-bis(trifluoromethyl)benzidine, and 10 to 60 mole %        4,4′-oxydianiline and in direct contact with the first imaged        metal layer and exposed areas of the first side of the first        electrically insulating layer. An adhesive layer is not present        between the first imaged metal layer and the first polyimide        coverlay. The first polyimide coverlay has a peel strength from        1 to 2 N/mm, as measured in accordance with IPC-TM-650-2.4.9d,        when the first polyimide coverlay is laminated to the first        imaged metal layer and exposed areas of the first side of the        first electrically insulating layer at a lamination temperature        from 320 to 380° C. and a pressure from 150 psi (10.55 Kg/cm) to        400 psi (28.13 Kg/cm). The first electrically insulating layer        is any electrically insulating material that can withstand the        lamination temperature from 320 to 380° C.

Another embodiment of the present disclosure is a polyimide coverlay fora circuit board. In such an embodiment, the circuit board, comprises:

-   -   a. a first electrically insulating layer having a first side and        a second side;    -   b. a first imaged metal layer;    -   c. a first polyimide coverlay derived from 100 mole %        3,3′,4,4′-biphenyl tetracarboxylic dianhydride, 20 to 30 mole %        2,2′-bis(trifluoromethyl)benzidine, and 70 to 80 mole %        4,4′-oxydianiline and in direct contact with the first imaged        metal layer and exposed areas of the first side of the first        electrically insulating layer. An adhesive layer is not present        between the first imaged metal layer and the first polyimide        coverlay. The first polyimide coverlay has a peel strength from        1 to 2 N/mm, as measured in accordance with IPC-TM-650-2.4.9d,        when the first polyimide coverlay is laminated to the first        imaged metal layer and exposed areas of the first side of the        first electrically insulating layer at a lamination temperature        from 320 to 380° C. and a pressure from 150 psi (10.55 Kg/cm) to        400 psi (28.13 Kg/cm). The first electrically insulating layer        is any electrically insulating material that can withstand the        lamination temperature from 320 to 380° C.

In some embodiments, the first polyimide coverlay is derived from 100mole % 3,3′,4,4′-biphenyl tetracarboxylic dianhydride, between andincluding any two of the following: 20, 30, 40, 45, 50, 55, 60, 65, 70,75, 80, 85 and 90 mole % 2,2′-bis(trifluoromethyl)benzidine, and betweenand including any two of the following: 10, 15, 20, 25, 30, 35, 40, 45,50, 55, 60, 70, and 80 mole % 4,4′-oxydianiline.

In some embodiments, the circuit board further comprises a second imagedmetal layer on the second side of the first electrically insulatinglayer.

In some embodiments, the circuit board further comprises a secondpolyimide coverlay derived from 100 mole % 3,3′,4,4′-biphenyltetracarboxylic dianhydride 20 to 90 mole %2,2′-bis(trifluoromethyl)benzidine, and 10 to 80 mole %4,4′-oxydianiline and in direct contact with the second imaged metallayer and exposed areas of the second side of the first electricallyinsulating layer. An adhesive layer is not present between the secondimaged metal layer and the second polyimide coverlay. The secondpolyimide coverlay has a peel strength from 0.7 to 2 N/mm, as measuredin accordance with IPC-TM-650-2.4.9d, when the second polyimide coverlayis laminated to the second imaged metal layer and the exposed areas ofthe second side of the first electrically insulating layer at alamination temperature from 300 to 380° C. and a pressure from 150 psi(10.55 Kg/cm) to 400 psi (28.13 Kg/cm).

In some embodiments, the circuit board further comprises a secondpolyimide coverlay derived from 100 mole % 3,3′,4,4′-biphenyltetracarboxylic dianhydride, 40 to 90 mole %2,2′-bis(trifluoromethyl)benzidine, and 10 to 60 mole %4,4′-oxydianiline and in direct contact with the second imaged metallayer and exposed areas of the second side of the first electricallyinsulating layer. An adhesive layer is not present between the secondimaged metal layer and the second polyimide coverlay. The secondpolyimide coverlay has a peel strength from 1 to 2 N/mm, as measured inaccordance with IPC-TM-650-2.4.9d, when the second polyimide coverlay islaminated to the second imaged metal layer and the exposed areas of thesecond side of the first electrically insulating layer at a laminationtemperature from 320 to 380° C. and a pressure from 150 psi (10.55Kg/cm) to 400 psi (28.13 Kg/cm).

In some embodiments, the second polyimide coverlay is derived from 100mole % 3,3′,4,4′-biphenyl tetracarboxylic dianhydride, between andincluding any two of the following: 20, 30, 40, 45, 50, 55, 60, 65, 70,75, 80, 85 and 90 mole % 2,2′-bis(trifluoromethyl)benzidine, and betweenand including any two of the following: 10, 15, 20, 25, 30, 35, 40, 45,50, 55, 60, 70 and 80 mole % 4,4′-oxydianiline.

In some embodiments, it is desirable for a coverlay to have opticalproperties which provide security against unwanted visual inspection andtampering of the electronic components. In some embodiments, the opticaldensity (opacity) desirable (e.g., to hide the conductor traces in theflex circuits from view) is greater than or equal to 2. An opticaldensity of 2 is intended to mean 1×10⁻² or 1% of light is transmittedthrough the film. The optical density is measured with a Macbeth TD904optical densitometer. The optical density can be increased by making athicker coverlay. This is undesirable since the trend is for coverlaysto be increasingly thin. The optical density can be increased by addingfiller. In some embodiments a pigment is added is increase the opticaldensity. In some embodiments, a matting agent is added to increase theoptical density. In some embodiments a combination of pigment andmatting agents can be added.

In some embodiments, the pigment is a low conductivity carbon black. Insome embodiments, the pigment is a non-carbon black pigment.

Virtually any pigment (or combination of pigments) can be used. In someembodiments, a low conductivity carbon black is used. Low conductivitycarbon black is intended to mean, channel type black or furnace black.In some embodiments, the low conductivity carbon black is a surfaceoxidized carbon black. One method for assessing the extent of surfaceoxidation (of the carbon black) is to measure the carbon black'svolatile content. The volatile content can be measured by calculatingweight loss when calcined at 950° C. for 7 minutes. Generally speaking,a highly surface oxidized carbon black (high volatile content) can bereadily dispersed into a polyamic acid solution (polyimide precursor),which in turn can be imidized into a (well dispersed) filled polyimidepolymer of the present disclosure. It is thought that if the carbonblack particles (aggregates) are not in contact with each other, thenelectron tunneling, electron hopping or other electron flow mechanismare generally suppressed, resulting in lower electrical conductivity. Insome embodiments, the low conductivity carbon black has a volatilecontent greater than or equal to 1%. In some embodiments, the lowconductivity carbon black has a volatile content greater than or equalto 5, 9, or 13%. In some embodiments, furnace black may be surfacetreated to increase the volatile content. In some embodiments a boneblack is used.

In some embodiment, the low conductivity carbon black is present inamount between and optionally including any two of the following: 2, 3,4, 5, 6, 7, 8 and 9 weight percent of the polyimide coverlay. In someembodiments, the first polyimide coverlay comprises a low conductivitycarbon black present in an amount from 2 to 9 weight percent. In someembodiments, the second polyimide coverlay comprises a low conductivitycarbon black present in an amount from 2 to 9 weight percent. In someembodiments, the first polyimide coverlay and the second polyimidecoverlay both comprises a low conductivity carbon black present in anamount from 2 to 9 weight percent.

In some embodiments, the first polyimide coverlay comprises a pigmentand a matting agent. In some embodiments, the first polyimide coverlay,the second polyimide coverlay or both comprise a pigment and a mattingagent.

In some embodiments, useful non-carbon black pigments include but arenot limited to the following: Barium Lemon Yellow, Cadmium Yellow Lemon,Cadmium Yellow Lemon, Cadmium Yellow Light, Cadmium Yellow Middle,Cadmium Yellow Orange, Scarlet Lake, Cadmium Red, Cadmium Vermilion,Alizarin Crimson, Permanent Magenta, Van Dyke brown, Raw Umber Greenish,or Burnt Umber. In some embodiments, useful black pigments include:cobalt oxide, Fe—Mn—Bi black, Fe—Mn oxide spinel black, (Fe,Mn)2O3black, copper chromite black spinel, lampblack, bone black, bone ash,bone char, hematite, black iron oxide, micaceous iron oxide, blackcomplex inorganic color pigments (CICP), CuCr2O4 black,(Ni,Mn,CoXCr,Fe)2O4 black, Aniline black, Perylene black, Anthraquinoneblack, Chromium Green-Black Hematite, Chrome Iron Oxide, Pigment Green17, Pigment Black 26, Pigment Black 27, Pigment Black 28, Pigment Brown29, Pigment Black 30, Pigment Black 32, Pigment Black 33 or mixturesthereof.

In some embodiments, the first polyimide coverlay comprises a non-carbonblack pigment present in an amount from 10 to 60 weight percent. In someembodiments, the second polyimide coverlay comprises a non-carbon blackpigment present in an amount from 10 to 60 weight percent. In someembodiments, the first polyimide coverlay, the second polyimide coverlayor both comprise a non-carbon black pigment present in an amount from 10to 60 weight percent. In some embodiments, the first polyimide coverlaycomprises a non-carbon black pigment present in an amount between andincluding any two of the following: 10, 20, 30, 40, 50 and 60 weightpercent. In some embodiments, the second polyimide coverlay comprises anon-carbon black pigment present in an amount between and including anytwo of the following: 10, 20, 30, 40, 50 and 60 weight percent.

In some embodiments, the first polyimide coverlay comprises a lowconductivity carbon black present in an amount from 2 to 9 weightpercent and the second polyimide coverlay comprises a non-carbon blackpigment present in an amount from 10 to 60 weight percent.

A uniform dispersion of isolated, individual particles (aggregates) notonly decreases the electrical conductivity, but additionally tends toproduce uniform color intensity. In some embodiments the lowconductivity carbon black is milled. In some embodiments, the meanparticle size of the low conductivity carbon black is between (andoptionally including) any two of the following sizes: 0.2, 0.3, 0.4,0.5, 0.6, 0.7, 0.8, 0.9 and 1.0 microns.

In some embodiments, dyes may be used. Examples of useful dye are, butnot limited to nigrosin black, monoazo chromium complex black, ormixtures thereof. In some embodiments, a mixture of dye and pigment maybe used.

In some embodiments it is desirable to have a coverlay with a matteappearance. Polymeric materials typically have inherent surface gloss.To control gloss (and thereby produce matte surface characteristics)various additive approaches are possible to achieve dull and low glosssurface characteristics. Broadly speaking, the additive approaches areall based upon the same fundamental physics—to create a modified surfacewhich is (on a micro-scale) coarse and irregular shaped and thereforeallows less light to be reflected back to the distant (e.g., greaterthan 50 centimeters) observer. When multiple rays of light hit a glossysurface, most of the light is reflected with similar angle and thereforea relatively high level of light reflectance can be observed. When thesame source of light hits a matte (ie. irregular) surface, the light isscattered in many different directions and also a much higher fractionis absorbed. Hence on rough surfaces, light tends to be diffuselyscattered in all directions, and the image forming qualities are largelydiminished (reflected objects no longer appear brilliant, but blurred).

Gloss meters used to characterize a specific surface for gloss level arebased on this same principle. Typically, a light source hits a surfaceat a fixed angle and after reflection the amount of reflected light isread by a photo cell. Reflection can be read at multiple angles. Maximumgloss performance for a perfectly glossy surface tends to demonstrate100% reflection, whereas a fully dull surface tends to demonstrate 0%reflection.

Silicas are inorganic particles that can be ground and filtered tospecific particle size ranges. The very irregular shape and porosity ofsilica particles and low cost make it a popular matting agent. Otherpotential matting agents can include: i. other ceramics, such as,borides, nitrides, carbides and other oxides (e.g., alumina, titania,etc); and ii. organic particles, provided the organic particle canwithstand the high temperature processing of a chemically convertedpolyimide (processing temperatures of from about 250° C. to about 550°C., depending upon the particular polyimide process chosen). One organicmatting agent that can withstand the thermal conditions of polyimidesynthesis are polyimide particles. In some embodiments, the mattingagent is polyimide particles. In some embodiments, the first polyimidecoverlay comprises polyimide particles. In some embodiments, the secondpolyimide coverlay comprises polyimide particles. In some embodiments,both the first polyimide coverlay and the second polyimide coverlaycomprise polyimide particles.

The amount of matting agent, median particle size and density must besufficient to produce the desired 60 degree gloss value. In someembodiments, the 60 degree gloss value is between and optionallyincluding any two of the following: 2, 5, 10, 15, 20, 25, 30 and 35. Insome embodiments, the 60 degree gloss value is from 10 to 35. In someembodiments, the 60 degree gloss value is from 2 to 25. The 60 degreegloss value is measured using Micro-TRI-Gloss gloss meter.

In some embodiments, the matting agent is present in an amount betweenand optionally including any two of the following: 1.6, 2, 3, 4, 5, 6,7, 8, 9 and 10 weight percent of the first polyimide coverlay or thesecond polyimide coverlay. In some embodiments, the matting agent has amedian particle size between and optionally including any two of thefollowing: 1.3, 2, 3, 4, 5, 6, 7, 8, 9 and 10 microns. The matting agentparticles should have an average particle size of less than (or equalto) about 10 microns and greater than (or equal to) about 1.3 microns.Larger matting agent particles may negatively impact mechanicalproperties. In some embodiments, the matting agent has a density betweenand optionally including any two of the following: 2, 3, 4 and 4.5 g/cc.In some embodiments, the matting agent is selected from the groupconsisting of silica, alumina, barium sulfate and mixtures thereof.

In some embodiments, the first polyimide coverlay comprises a pigmentand a matting agent. In some embodiments, the pigment and the mattingagent are both a low conductivity carbon black and in such embodiments,the low conductivity carbon black is present in the first polyimidecoverlay in an amount from 2 to 20 weight percent. In some embodiments,the pigment and the matting agent are both a low conductivity carbonblack and in such embodiments, the low conductivity carbon black ispresent in the first polyimide coverlay in an amount between andincluding any two of the following: 2, 5, 10, 15 and 20 weight percent.In some embodiments, the pigment and the matting agent are both a lowconductivity carbon black and in such embodiments, the low conductivitycarbon black is present in the second polyimide coverlay in an amountbetween and including any two of the following: 2, 5, 10, 15 and 20weight percent.

In some embodiments, the second polyimide coverlay comprises a pigmentand a matting agent. In some embodiments, the pigment and the mattingagent in both the first polyimide coverlay and the second polyimidecoverlay are a low conductivity carbon black and the low conductivitycarbon black is present in the first polyimide coverlay in an amountfrom 2 to 20 weight percent and the low conductivity carbon black ispresent in the second polyimide coverlay in an amount from 2 to 20weight percent. In some embodiments, the pigment and the matting agentare both a low conductivity carbon black and the low conductivity carbonblack is present in the first polyimide coverlay in an amount from 2 to20 weight percent. In some embodiments, the pigment and the mattingagent are both a low conductivity carbon black and the low conductivitycarbon black is present in the first polyimide coverlay, the secondpolyimide coverlay or both in an amount from 2 to 20 weight percent.

In some embodiments, the first polyimide coverlay comprises a lowconductivity carbon black present in an amount from 2 to 9 weightpercent and the second polyimide coverlay comprises a non-carbon blackpigment present in an amount from 10 to 60 weight percent.

In another embodiment, the first polyimide coverlay comprises a lowconductivity carbon black present in an amount from 2 to 9 weightpercent and the second polyimide coverlay comprises a pigment and amatting agent. In another embodiment, the pigment and the matting agentin the second polyimide coverlay are both a low conductivity carbonblack, the carbon black present in an amount from 2 to 20 weightpercent.

In another embodiment, the first polyimide coverlay comprises a lowconductivity carbon black present in an amount from 2 to 9 weightpercent and the second polyimide coverlay comprises a pigment and amatting agent, and wherein the matting agent is polyimide particles.

In another embodiment, the first polyimide coverlay is derived from 100mole % 3,3′,4,4′-biphenyl tetracarboxylic dianhydride, and 100 mole %2,2′-bis(trifluoromethyl)benzidine; In such an embodiment, the circuitboard comprises

-   -   a. a first electrically insulating layer having a first side and        a second side;    -   b. a first imaged metal layer;    -   c. a first polyimide coverlay derived from 100 mole %        3,3′,4,4′-biphenyl tetracarboxylic dianhydride, and 100 mole %        2,2′-bis(trifluoromethyl)benzidine and in direct contact with        the first imaged metal layer and exposed areas of the first side        of the electrically insulating layer. An adhesive layer is not        present between the first imaged metal layer and the first        polyimide coverlay. The first polyimide coverlay has a peel        strength from 1 to 2 N/mm, as measured in accordance with        IPC-TM-650-2.4.9d, when the first polyimide coverlay is        laminated to the first imaged metal layer and the exposed areas        of the first side of the first electrically insulating layer at        a lamination temperature from 380 to 400° C. and a pressure from        150 psi (10.55 Kg/cm) to 400 psi (28.13 Kg/cm) and the first        electrically insulating layer is any electrically insulating        material that can withstand the lamination temperature from 380        to 400° C.

In some embodiments, circuit board further comprises a second polyimidecoverlay derived from 100 mole % 3,3′,4,4′-biphenyl tetracarboxylicdianhydride, and 100 mole % 2,2′-bis(trifluoromethyl)benzidine. In suchembodiments, the circuit board comprises

-   -   a. a second polyimide coverlay derived from 100 mole %        3,3′,4,4′-biphenyl tetracarboxylic dianhydride, and 100 mole %        2,2′-bis(trifluoromethyl)benzidine and in direct contact with        the second imaged metal layer and exposed areas of the second        side of the first electrically insulating layer.    -   b. a second imaged metal layer    -   c. a first electrically insulating layer having a first side and        a second side;    -   d. a first imaged metal layer;    -   e. a first polyimide coverlay derived from 100 mole %        3.3′,4,4′-biphenyl tetracarboxylic dianhydride, and 100 mole %        2,2′-bis(trifluoromethyl) benzidine. and in direct contact with        the first imaged metal layer and exposed areas of the first side        of the first electrically insulating layer.        An adhesive layer is not present between the first imaged metal        layer and the first polyimide coverlay and an adhesive layer is        not present between the second imaged metal layer and the second        polyimide coverlay. The first polyimide coverlay has a peel        strength from 1 to 2 N/mm, as measured in accordance with        IPC-TM-650-2.4.9d, when the polyimide coverlay is laminated to        the first imaged metal layer and exposed areas of the first side        of the first electrically insulating layer at a lamination        temperature from 380 to 400° C. and a pressure from 1 50 psi        (10.55 Kg/cm) to 400 psi (28.13 Kg/cm) and the first        electrically insulating layer is any electrically insulating        material that can withstand the lamination temperature from 380        to 400° C.

Electrically Insulating Layer—Circuit Board Coverlay

In some embodiments, the first electrically insulating layer is anyelectrically insulating material that can withstand the laminationtemperature from 300 to 400° C.; in some embodiments 300 to 380° C. orin other embodiments 320 to 380° C. In some embodiments, the firstelectrically insulating layer is derived from a polyimide. In someembodiments, the first electrically insulating layer is derived from anaromatic polyimide.

In some embodiments, the first electrically insulating layer is derivedfrom 100 mole % 3,3′,4,4′-biphenyl tetracarboxylic dianhydride, 20 to 90mole % 2,2′-bis(trifluoromethyl)benzidine and 10 to 80 mole %4,4′-oxydianiline.

In some embodiments the first electrically insulating layer is derivedfrom 100 mole % 3,3′,4,4′-biphenyl tetracarboxylic dianhydride, 40 to 90mole % 2,2′-bis(trifluoromethyl)benzidine

In some embodiments the first electrically insulating layer is derivedfrom 100 mole % 3,3′,4,4′-biphenyl tetracarboxylic dianhydride, 100 mole% 2,2′-bis(trifluoromethyl)benzidine.

In some embodiments the first electrically insulating layer is derivedfrom 100 mole % 3,3′,4,4′-biphenyl tetracarboxylic dianhydride, 20 to 30mole % 2,2′-bis(trifluoromethyl)benzidine.

In some embodiments, the first electrically insulating layer is derivedfrom 100 mole % 3,3′,4,4′-biphenyl tetracarboxylic dianhydride, betweenand including any two of the following: 20, 30, 40, 45, 50, 55, 60, 65,70, 75, 80, 85 and 90 mole % 2,2′-bis(trifluoromethyl)benzidine, andbetween and including any two of the following: 10, 15, 20, 25, 30, 35,40, 45, 50, 55 60, 70 and 80 mole % 4,4′-oxydianiline.

In some embodiments, the first electrically insulating layer comprisesfrom 1 to 55 weight percent of a thermally conductive filler, adielectric filler or mixtures thereof.

Imaged Metal Layers—Circuit Board Coverlay

In some embodiments, the first imaged metal layer is copper. In someembodiments, the first imaged metal layer, the second imaged layer orboth are copper. In some embodiments, the first imaged metal layer iselemental metal. In some embodiments, the first imaged metal layer is ametal alloy. In some embodiments, the first imaged metal layer isaluminum.

In some embodiments, the second imaged metal layer is elemental metal.In some embodiments, the second imaged metal layer is a metal alloy. Insome embodiments, the second imaged metal layer is copper. In someembodiments, the second imaged metal layer is aluminum.

In some embodiments, both the first imaged metal layer and the secondimaged metal layer are elemental metal. In some embodiments, both thefirst imaged metal layer and the second imaged metal layer are a metalalloy. In some embodiments, the first imaged metal layer and the secondimaged metal layer are copper.

In some embodiments, the metal alloy comprises 50 to 72 weight % nickel.In another embodiment, the metal alloy comprises 50 to 72% weight %nickel and 14 to 24 weight % Chromium. In some embodiments, the metalfoil is aluminum.

In some embodiments, the first imaged metal layer is from 5 to 72microns thick. In some embodiments, the first imaged metal layer isbetween and including any two of the following: 5, 10, 15, 20, 25, 30,35, 40, 45, 50, 55, 60, 65, 70 and 72 microns thick. In someembodiments, the first imaged metal layer is surface treated to improveadhesion to electrically insulating layers.

In some embodiments, the second imaged metal layer is from 5 to 72microns thick. In some embodiments, the second imaged metal layer isbetween and including any two of the following: 5, 10, 15, 20, 25, 30,35, 40, 45, 50, 55, 60, 65, 70 and 72 microns thick. In someembodiments, the second imaged metal layer is surface treated to improveadhesion to electrically insulating layers.

In some embodiments, the first imaged metal layer and the second imagedmetal layer are made by imaging a metal foil/metal layer with aphotoresist and copper etching to created imaged metal layers havinglines of different widths using standard procedures in the flexibleprinted circuit board industry.

In some embodiments, the first electrically insulating layer comprisesfrom 1 to 55 weight percent of a thermally conductive filler, adielectric filler or mixtures thereof, the first imaged metal layer iscopper and wherein the first polyimide coverlay comprises: a lowconductivity carbon black present in an amount from 2 to 9 weightpercent or a non-carbon black pigment present in an amount from 10 to 60weight percent.

In another embodiment, the first electrically insulating layer comprisesfrom 1 to 55 weight percent of a thermally conductive filler, adielectric filler or mixtures thereof; the first imaged metal layer iscopper and wherein the first polyimide coverlay comprises a pigment anda matting agent, wherein the pigment and the matting agent are both alow conductivity carbon black, the low conductivity carbon black ispresent in the first polyimide coverlay in an amount from 2 to 20 weightpercent.

In another embodiment, the first electrically insulating layer comprisesfrom 1 to 55 weight percent of a thermally conductive filler, adielectric filler or mixtures thereof; the first imaged metal layer iscopper and wherein the first polyimide coverlay comprises a pigment anda matting agent, wherein the matting agent is polyimide particles.

In some embodiments, the first electrically insulating layer comprisesfrom 1 to 55 weight percent of a thermally conductive filler, adielectric filler or mixtures thereof and the first imaged metal layer,the second imaged metal layer or both are copper.

In some embodiments, the first electrically insulating layer comprisesfrom 1 to 55 weight percent of a thermally conductive filler, adielectric filler or mixtures thereof. In some embodiments, the firstelectrically insulating layer comprises from 1 to 55 weight percent of athermally conductive filler, a dielectric filler or mixtures thereof andthe first imaged metal layer is copper. In some embodiments, first theelectrically insulating layer comprises between and including any two ofthe following: 1, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50 and 55 weightpercent of a thermally conductive filler, a dielectric filler ormixtures thereof. In some embodiments, the first electrically insulatinglayer comprises between and including any two of the following: 1, 5,10, 15, 20, 25, 30, 35, 40, 45, 50 and 55 weight percent of a thermallyconductive filler, a dielectric filler or mixtures thereof and the firstimaged metal layer is copper.

In some embodiments of the present disclosure, the circuit boardcomprises:

-   -   a. a second polyimide coverlay derived from 100 mole %        3,3′,4,4′-biphenyl tetracarboxylic dianhydride, 20 to 90 mole %        2,2′-bis(trifluoromethyl)benzidine, and 10 to 80 mole %        4,4′-oxydianiline and in direct contact with the second imaged        metal layer and exposed areas of the second side of the first        electrically insulating layer. An adhesive layer is not present        between the second imaged metal layer and the second polyimide        coverlay. The second polyimide coverlay has a peel strength from        0.7 to 2 N/mm, as measured in accordance with IPC-TM-650-2.4.9d,        when the second polyimide coverlay is laminated to the second        imaged metal layer and the exposed areas of the second side of        the first electrically insulating layer at a lamination        temperature from 300 to 380° C. and a pressure from 1 50 psi        (10.55 Kg/cm) to 400 psi (28.13 Kg/cm);    -   b. a second imaged metal layer;    -   c. a first electrically insulating layer having a first side and        a second side;    -   d. a first imaged metal layer;    -   e. a first polyimide coverlay derived from 100 mole %        3,3′,4,4′-biphenyl tetracarboxylic dianhydride, 20 to 90 mole %        2,2′-bis(trifluoromethyl)benzidine, and 10 to 80 mole %        4,4′-oxydianiline and in direct contact with the first imaged        metal layer and exposed areas of the first side of the first        electrically insulating layer. An adhesive layer is not present        between the first imaged metal layer and the first polyimide        coverlay. The first polyimide coverlay has a peel strength from        0.7 to 2 N/mm, as measured in accordance with IPC-TM-650-2.4.9d,        when the first polyimide coverlay is laminated to the first        imaged metal layer and exposed areas of the first side of the        first electrically insulating layer at a lamination temperature        from 300 to 380° C. and a pressure from 150 psi (10.55 Kg/cm) to        400 psi (28.13 Kg/cm). The first electrically insulating layer        is any electrically insulating material that can withstand the        lamination temperature from 300 to 380° C.

In some embodiments of the present disclosure, the circuit boardcomprises:

-   -   a. a second polyimide coverlay derived from 100 mole %        3,3′,4,4′-biphenyl tetracarboxylic dianhydride, 20 to 90 mole %        2,2′-bis(trifluoromethyl)benzidine, and 10 to 80 mole %        4,4′-oxydianiline and in direct contact with the second imaged        metal layer and exposed areas of the second side of the first        electrically insulating layer. An adhesive layer is not present        between the second imaged metal layer and the second polyimide        coverlay. The second polyimide coverlay has a peel strength from        0.7 to 2 N/mm, as measured in accordance with IPC-TM-650-2.4.9d,        when the second polyimide coverlay is laminated to the second        imaged metal layer and the exposed areas of the second side of        the first electrically insulating layer at a lamination        temperature from 300 to 380° C. and a pressure from 1 50 psi        (10.55 Kg/cm) to 400 psi (28.13 Kg/cm);    -   b. a second imaged metal layer;    -   c. a first electrically insulating layer having a first side and        a second side; the first electrically insulating layer is        derived from 100 mole % 3,3′,4,4′-biphenyl tetracarboxylic        dianhydride, 20 to 90 mole % 2,2′-bis(trifluoromethyl)benzidine,        and 10 to 80 mole % 4,4′-oxydianiline or is derived from 100        mole % 3,3′,4,4′-biphenyl tetracarboxylic dianhydride 100 mole %        2,2′-bis(trifluoromethyl)benzidine.    -   d. a first imaged metal layer;    -   e. a first polyimide coverlay derived from 100 mole %        3,3′,4,4′-biphenyl tetracarboxylic dianhydride, 20 to 90 mole %        2,2′-bis(trifluoromethyl)benzidine, and 10 to 80 mole %        4,4′-oxydianiline and in direct contact with the first imaged        metal layer and exposed areas of the first side of the first        electrically insulating layer. An adhesive layer is not present        between the first imaged metal layer and the first polyimide        coverlay. The first polyimide coverlay has a peel strength from        0.7 to 2 N/mm, as measured in accordance with IPC-TM-650-2.4.9d,        when the first polyimide coverlay is laminated to the first        imaged metal layer and exposed areas of the first side of the        first electrically insulating layer at a lamination temperature        from 300 to 380° C. and a pressure from 150 psi (10.55 Kg/cm) to        400 psi (28.13 Kg/cm). The first electrically insulating layer        is any electrically insulating material that can withstand the        lamination temperature from 300 to 380° C.

In some embodiments of the present disclosure, the circuit boardcomprises:

-   -   a. a second polyimide coverlay derived from 100 mole %        3,3′,4,4′-biphenyl tetracarboxylic dianhydride, 40 to 90 mole %        2,2′-bis(trifluoromethyl)benzidine, and 10 to 60 mole %        4,4′-oxydianiline and in direct contact with the second imaged        metal layer and exposed areas of the second side of the first        electrically insulating layer. An adhesive layer is not present        between the second imaged metal layer and the second polyimide        coverlay. The second polyimide coverlay has a peel strength from        1 to 2 N/mm, as measured in accordance with IPC-TM-650-2.4.9d,        when the second polyimide coverlay is laminated to the second        imaged metal layer and the exposed areas of the second side of        the first electrically insulating layer at a lamination        temperature from 320 to 380° C. and a pressure from 1 50 psi        (10.55 Kg/cm) to 400 psi (28.13 Kg/cm);    -   b. a second imaged metal layer,    -   c. a first electrically insulating layer having a first side and        a second side;    -   d. a first imaged metal layer;    -   e. a first polyimide coverlay derived from 100 mole %        3,3′,4,4′-biphenyl tetracarboxylic dianhydride, 40 to 90 mole %        2,2′-bis(trifluoromethyl)benzidine, and 10 to 60 mole %        4,4′-oxydianiline and in direct contact with the first imaged        metal layer and exposed areas of the first side of the first        electrically insulating layer. An adhesive layer is not present        between the first imaged metal layer and the first polyimide        coverlay. The first polyimide coverlay has a peel strength from        1 to 2 N/mm, as measured in accordance with IPC-TM-650-2.4.9d,        when the first polyimide coverlay is laminated to the first        imaged metal layer and exposed areas of the first side of the        first electrically insulating layer at a lamination temperature        from 320 to 380° C. and a pressure from 150 psi (10.55 Kg/cm) to        400 psi (28.13 Kg/cm). The first electrically insulating layer        is any electrically insulating material that can withstand the        lamination temperature from 320 to 380° C.

In some embodiments of the present disclosure, the circuit boardcomprises:

-   -   a. a second polyimide coverlay derived from 100 mole %        3,3′,4,4′-biphenyl tetracarboxylic dianhydride, 40 to 90 mole %        2,2′-bis(trifluoromethyl)benzidine, and 10 to 60 mole %        4,4′-oxydianiline and in direct contact with the second imaged        metal layer and exposed areas of the second side of the first        electrically insulating layer. An adhesive layer is not present        between the second imaged metal layer and the second polyimide        coverlay. The second polyimide coverlay has a peel strength from        1 to 2 N/mm, as measured in accordance with IPC-TM-650-2.4.9d,        when the second polyimide coverlay is laminated to the second        imaged metal layer and the exposed areas of the second side of        the first electrically insulating layer at a lamination        temperature from 320 to 380° C. and a pressure from 1 50 psi        (10.55 Kg/cm) to 400 psi (28.13 Kg/cm);    -   b. a second imaged metal layer;    -   c. a first electrically insulating layer having a first side and        a second side; the first electrically insulating layer is        derived from 100 mole % 3,3′,4,4′-biphenyl tetracarboxylic        dianhydride, 40 to 90 mole % 2,2′-bis(trifluoromethyl)benzidine,        and 10 to 60 mole % 4,4′-oxydianiline or is derived from 100        mole % 3,3′,4,4′-biphenyl tetracarboxylic dianhydride, 100 mole        % 2,2′-bis(trifluoromethyl)benzidine.    -   d. a first imaged metal layer;    -   e. a first polyimide coverlay derived from 100 mole %        3,3′,4,4′-biphenyl tetracarboxylic dianhydride, 40 to 90 mole %        2,2′-bis(trifluoromethyl)benzidine, and 10 to 60 mole %        4,4′-oxydianiline and in direct contact with the first imaged        metal layer and exposed areas of the first side of the first        electrically insulating layer. An adhesive layer is not present        between the first imaged metal layer and the first polyimide        coverlay. The first polyimide coverlay has a peel strength from        1 to 2 N/mm, as measured in accordance with IPC-TM-650-2.4.9d,        when the first polyimide coverlay is laminated to the first        imaged metal layer and exposed areas of the first side of the        first electrically insulating layer at a lamination temperature        from 320 to 380° C. and a pressure from 150 psi (10.55 Kg/cm) to        400 psi (28.13 Kg/cm). The first electrically insulating layer        is any electrically insulating material that can withstand the        lamination temperature from 320 to 380° C.

In some embodiments, the first polyimide coverlay and the secondpolyimide coverlay each independently have a thickness from 5 to 152microns. In some embodiments, the first polyimide coverlay has athickness between and including any two of the following: 5, 10, 20, 30,40, 50, 60, 70, 80, 90, 100, 105, 110, 120, 130, 140 and 152 microns. Insome embodiments, the second polyimide coverlay has a thickness betweenand including any two of the following: 5, 10, 20, 30, 40, 50, 60, 70,80, 90, 100, 105, 110, 120, 130, 140 and 152 microns. In someembodiments, the first polyimide coverlay and the second polyimidecoverlay each independently have a thickness from 5 to 105 micron. Inyet another embodiment, the first polyimide coverlay and the secondpolyimide coverlay each independently have a thickness from 10 to 40microns.

The polyimide coverlay(s) of the present disclosure can be made by anyknown thermal conversion or chemical conversion method for making filledpolyimides. In some embodiments, it is desirable to use chemicalconversion due to the advantages chemical conversion over thermalconversion such as but not limited to, lower CTE and films are matte onboth sides even when cast on to a smooth surface.

In some embodiments, the circuit board is made by taking a single-sidedclad (electrically insulating layer and an imaged metal layer) andlaminating with a first polyimide coverlay at a lamination temperatureof 320 to 380° C. and a pressure from 150 psi (10.55 Kg/cm) to 400 psi(28.13 Kg/cm) such that the first polyimide coverlay is in directcontact with the first imaged metal layer and exposed areas of the firstside of the first electrically insulating layer.

In some embodiments, the circuit board is made by taking a double-sidedclad (first imaged metal layer, first electrically insulating layer anda second imaged metal layer) and laminating with a first polyimidecoverlay and a second polyimide coverlay at a lamination temperature of320 to 380° C. and a pressure from 150 psi (10.55 Kg/cm) to 400 psi(28.13 Kg/cm) such that the first polyimide coverlay is in directcontact with the first imaged metal layer and exposed areas of the firstside of the first electrically insulating layer and the second polyimidecoverlay is laminated to the second imaged metal layer and the exposedareas of the second side of the first electrically insulating layer.

In some embodiments, a vacuum platen press is used.

Circuit Board—Polyimide Bondply

One embodiment of the present disclosure is a polyimide bondply for acircuit board. In such an embodiment, the circuit board comprises, inthe following order:

-   -   a. a first imaged metal layer    -   b. a first electrically insulating layer having a first side and        a second side; the first side of the first electrically        insulating layer is next to the first imaged metal layer    -   c. a second imaged metal layer; the second side of the first        electrically insulating layer is next to the second imaged metal        layer;    -   d. a polyimide bondply derived from 100 mole %        3,3′,4,4′-biphenyl tetracarboxylic dianhydride, 20 to 90 mole %        2,2′-bis(trifluoromethyl)benzidine, and 10 to 80 mole %        4,4′-oxydianiline;    -   e. a third imaged metal layer;    -   f. a second electrically insulating layer having a first side        and a second side; the first side of the second electrically        insulating layer is next to the third imaged metal layer    -   g. a fourth imaged metal layer; the second side of the second        electrically insulating layer is next to the fourth imaged metal        layer. The polyimide bondply is in direct contact with the        second imaged metal layer and exposed areas of the second side        of the first electrically insulating layer and in direct contact        with the third imaged metal layer and exposed areas of the first        side of the second electrically insulating layer. In some        embodiments, the polyimide bondply has a peel strength from 0.7        to 2 N/mm as measured in accordance with IPC-TM-650-2.4.9d, when    -   i) the first imaged metal layer, the first electrically        insulating layer and the second image metal layer; and    -   ii) the polyimide bondply;    -   iii) the third imaged metal layer, the second electrically        insulating layer and the fourth imaged metal layer are laminated        at a lamination temperature from 300 to 380° C. and a pressure        from 150 psi (10.55 Kg/cm) to 400 psi (28.13 Kg/cm). The first        electrically insulating layer and the second electrically        insulating layer are any electrically insulating material that        can withstand the lamination temperature from 300 to 380° C.

Another embodiment of the present disclosure is a polyimide bondply fora circuit board. In such an embodiment, the circuit board comprises, inthe following order:

-   -   a. a first imaged metal layer    -   b. a first electrically insulating layer having a first side and        a second side; the first side of the first electrically        insulating layer is next to the first imaged metal layer    -   c. a second imaged metal layer; the second side of the first        electrically insulating layer is next to the second imaged metal        layer;    -   d. a polyimide bondply derived from 100 mole %        3,3′,4,4′-biphenyl tetracarboxylic dianhydride, 40 to 90 mole %        2,2′-bis(trifluoromethyl)benzidine, and 10 to 60 mole %        4,4′-oxydianiline;    -   e. a third imaged metal layer;    -   f. a second electrically insulating layer having a first side        and a second side; the first side of the second electrically        insulating layer is next to the third imaged metal layer    -   g. a fourth imaged metal layer; the second side of the second        electrically insulating layer is next to the fourth imaged metal        layer. The polyimide bondply is in direct contact with the        second imaged metal layer and exposed areas of the second side        of the first electrically insulating layer and in direct contact        with the third imaged metal layer and exposed areas of the first        side of the second electrically insulating layer. The polyimide        bondply has a peel strength from 1 to 2 N/mm as measured in        accordance with IPC-TM-650-2.4.9d, when    -   i) the first imaged metal layer, the first electrically        insulating layer and the second image metal layer; and    -   ii) the polyimide bondply;    -   iii) the third imaged metal layer, the second electrically        insulating layer and the fourth imaged metal layer are laminated        at a lamination temperature from 320 to 380° C. and a pressure        from 150 psi (10.55 Kg/cm) to 400 psi (28.13 Kg/cm). The first        electrically insulating layer and the second electrically        insulating layer are any electrically insulating material that        can withstand the lamination temperature from 320 to 380° C.

In some embodiments, the polyimide bondply is derived from 100 mole %3,3′,4,4′-biphenyl tetracarboxylic dianhydride, between and includingany two of the following: 20, 30, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85and 90 mole % 2,2′-bis(trifluoromethyl)benzidine, and between andincluding any two of the following: 10, 15, 20, 25, 30, 35, 40, 45, 50,55, 60, 70 and 80 mole % 4,4′-oxydianiline.

In some embodiments, the polyimide bondply comprises from 1 to 55 weightpercent of a thermally conductive filler, dielectric filler or mixturesthereof. In some embodiments, the polyimide bondply comprises betweenand including any two of the following: 1, 5, 10, 15, 20, 25, 30, 35,40, 45, 50 and 55 weight percent of a thermally conductive filler, adielectric filler or mixtures thereof.

In another embodiment, the polyimide bondply is derived from 100 mole %3,3′,4,4′-biphenyl tetracarboxylic dianhydride, and 100 mole %2,2′-bis(trifluoromethyl)benzidine and can be laminated at a laminationtemperature from 380 to 400° C. and a pressure from 150 psi (10.55Kg/cm) to 400 psi (28.13 Kg/cm).

Electrically Insulating Layers—Circuit Board Bondply

In some embodiments, the first electrically insulating layer is anyelectrically insulating material that can withstand the laminationtemperature from 300 to 380° C. In some embodiments, the firstelectrically insulating layer is derived from a polyimide. In someembodiments, the first electrically insulating layer is derived from anaromatic polyimide.

In some embodiments, the second electrically insulating layer is anyelectrically insulating material that can withstand the laminationtemperature from 300 to 380° C.

In some embodiments, the second electrically insulating layer is derivedfrom a polyimide. In some embodiments, the second electricallyinsulating layer is derived from an aromatic polyimide.

In one embodiment, the first electrically insulating layer and thesecond electrically insulating layer are any electrically insulatingmaterial that can withstand the lamination temperature from 320 to 380°C.

In some embodiments, the first electrically insulating layer is derivedfrom 100 mole % 3,3′,4,4′-biphenyl tetracarboxylic dianhydride, 20 to 90mole % 2,2′-bis(trifluoromethyl)benzidine and 10 to 80 mole %4,4′-oxydianiline.

In some embodiments the first electrically insulating layer is derivedfrom 100 mole % 3,3′,4,4′-biphenyl tetracarboxylic dianhydride, 40 to 90mole % 2,2′-bis(trifluoromethyl)benzidine

In some embodiments the first electrically insulating layer is derivedfrom 100 mole % 3,3′,4,4′-biphenyl tetracarboxylic dianhydride, 100 mole% 2,2′-bis(trifluoromethyl)benzidine.

In some embodiments the first electrically insulating layer is derivedfrom 100 mole % 3,3′,4,4′-biphenyl tetracarboxylic dianhydride, 20 to 30mole % 2,2′-bis(trifluoromethyl)benzidine.

In some embodiments, the first electrically insulating layer, the secondelectrically insulating layer or both are derived from 100 mole %3,3′,4,4′-biphenyl tetracarboxylic dianhydride, between and includingany two of the following: 20, 30, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85and 90 mole % 2,2′-bis(trifluoromethyl)benzidine, and between andincluding any two of the following: 10, 15, 20, 25, 30, 35, 40, 45, 50,55 60, 70 and 80 mole % 4,4′-oxydianiline.

In some embodiments, the first electrically insulating layer is derivedfrom 100 mole % 3,3′,4,4′-biphenyl tetracarboxylic dianhydride, 40 to 90mole % 2,2′-bis(trifluoromethyl)benzidine, and 10 to 60 mole %4,4′-oxydianiline and is direct contact with first imaged metal layer,the second imaged metal layer and exposed areas of the polyimidebondply.

In some embodiments, the second electrically insulating layer is derivedfrom 100 mole % 3,3′,4,4′-biphenyl tetracarboxylic dianhydride, 40 to 90mole % 2,2′-bis(trifluoromethyl)benzidine, and 10 to 60 mole %4,4′-oxydianiline and is direct contact with fourth imaged metal layer,the third imaged metal layer and exposed areas of the polyimide bondply.

In some embodiments, the first electrically insulating layer is derivedfrom 100 mole % 3,3′,4,4′-biphenyl tetracarboxylic dianhydride, 20 to 90mole % 2,2′-bis(trifluoromethyl)benzidine, and 10 to 80 mole %4,4′-oxydianiline and is direct contact with first imaged metal layer,the second imaged metal layer and exposed areas of the polyimide bondplyand the second electrically insulating layer is derived from 100 mole %3,3′,4,4′-biphenyl tetracarboxylic dianhydride, 20 to 90 mole %2,2′-bis(trifluoromethyl)benzidine, and 10 to 80 mole %4,4′-oxydianiline and is direct contact with fourth imaged metal layer,the third imaged metal layer and exposed areas of the polyimide bondply.

In some embodiments, the first electrically insulating layer is derivedfrom 100 mole % 3,3′,4,4′-biphenyl tetracarboxylic dianhydride, 40 to 90mole % 2,2′-bis(trifluoromethyl)benzidine, and 10 to 60 mole %4,4′-oxydianiline and is direct contact with first imaged metal layer,the second imaged metal layer and exposed areas of the polyimide bondplyand the second electrically insulating layer is derived from 100 mole %3,3′,4,4′-biphenyl tetracarboxylic dianhydride, 40 to 90 mole %2,2′-bis(trifluoromethyl)benzidine, and 10 to 60 mole %4,4′-oxydianiline and is direct contact with fourth imaged metal layer,the third imaged metal layer and exposed areas of the polyimide bondply.

In another embodiment, the first electrically insulating layer isderived from 100 mole % 3,3′,4,4′-biphenyl tetracarboxylic dianhydride,and 100 mole % 2,2′-bis(trifluoromethyl)benzidine and can be laminatedat a lamination temperature from 380 to 400° C. and a pressure from 150psi (10.55 Kg/cm) to 400 psi (28.13 Kg/cm).

In another embodiment, the second electrically insulating layer isderived from 100 mole % 3,3′,4,4′-biphenyl tetracarboxylic dianhydride,and 100 mole % 2,2′-bis(trifluoromethyl)benzidine and can be laminatedat a lamination temperature from 380 to 400° C. and a pressure from 150psi (10.55 Kg/cm) to 400 psi (28.13 Kg/cm).

In some embodiments, the first electrically insulating layer is derivedfrom 100 mole % 3,3′,4,4′-biphenyl tetracarboxylic dianhydride, and 100mole % 2,2′-bis(trifluoromethyl)benzidine and is direct contact withfirst imaged metal layer, the second imaged metal layer and exposedareas of the polyimide bondply and the second electrically insulatinglayer is derived from 100 mole % 3,3′,4,4′-biphenyl tetracarboxylicdianhydride, and 100 mole % 2,2′-bis(trifluoromethyl)benzidine and isdirect contact with fourth imaged metal layer, the third imaged metallayer and exposed areas of the polyimide bondply.

In some embodiments, the first electrically insulating layer comprisesfrom 1 to 55 weight percent of a thermally conductive filler, dielectricfillers or mixtures thereof. In some embodiments, the secondelectrically insulating layer comprises from 1 to 55 weight percent of athermally conductive filler, dielectric fillers or mixtures thereof. Insome embodiments, the first electrically insulating layer, the secondelectrically insulating layer or both comprise from 1 to 55 weightpercent of a thermally conductive filler, dielectric filler or mixturesthereof.

In some embodiments, the first electrically insulating layer, the secondelectrically insulating layer or both comprise from 1 to 55 weightpercent of a thermally conductive filler, a dielectric filler ormixtures thereof.

Imaged Metal Layers—Circuit Board Bondply

In some embodiments, the first imaged metal layer is elemental metal. Insome embodiments, the first imaged metal layer is a metal alloy. In someembodiments, the first imaged metal layer is copper. In someembodiments, the first imaged metal layer is aluminum.

In some embodiments, the second imaged metal layer is elemental metal.In some embodiments, the second imaged metal layer is a metal alloy. Insome embodiments, the second imaged metal layer is copper. In someembodiments, the second imaged metal layer is aluminum.

In some embodiments, the third imaged metal layer is elemental metal. Insome embodiments, the third imaged metal layer is a metal alloy. In someembodiments, the third imaged metal layer is copper. In someembodiments, the third imaged metal layer is aluminum.

In some embodiments, the fourth imaged metal layer is elemental metal.In some embodiments, the fourth imaged metal layer is a metal alloy. Insome embodiments, the fourth imaged metal layer is copper. In someembodiments, the fourth imaged metal layer is aluminum.

In some embodiments, the first imaged metal layer, the second imagedmetal layer, the third imaged metal layer and the fourth imaged metallayer are elemental metal. In some embodiments, the first imaged metallayer, the second imaged metal layer, the third imaged metal layer andthe fourth imaged metal layer are a metal alloy. In some embodiments,the first imaged metal layer, the second imaged metal layer, the thirdimaged metal layer and the fourth imaged metal layer are copper. In someembodiments, the first imaged metal layer, the second imaged metallayer, the third imaged metal layer and the fourth imaged metal layerare aluminum.

In some embodiments, the metal alloy comprises 50 to 72 weight % nickel.In another embodiment, the metal alloy comprises 50 to 72% weight %nickel and 14 to 24 weight % Chromium.

In some embodiments, the first imaged metal layer, the second imagedmetal layer, the third imaged metal layer and the fourth imaged metallayer are independently from 5 to 72 microns thick. In some embodiments,the first imaged metal layer, the second imaged metal layer, the thirdimaged metal layer and the fourth imaged metal layer are independentlybetween and including any two of the following: 5, 10, 15, 20, 25, 30,35, 40, 45, 50, 55, 60, 65, 70 and 72 microns thick. In someembodiments, the first imaged metal layer, the second imaged metallayer, the third imaged metal layer and the fourth imaged metal layerare independently surface treated to improve adhesion to electricallyinsulating layers.

In some embodiments, the first imaged metal layer, the second imagedmetal layer, the third imaged metal layer and the fourth imaged metallayer are made by imaging a metal foil/metal layer with a photoresistand copper etching to created imaged metal layers having lines ofdifferent widths using standard procedures in the flexible printedcircuit board industry.

In one embodiment, the polyimide bondply comprises from 1 to 55 weightpercent of a thermally conductive filler, dielectric fillers or mixturesthereof and the first electrically insulating layer, the secondelectrically insulating layer or both comprise from 1 to 55 weightpercent of a thermally conductive filler, dielectric fillers or mixturesthereof and the first imaged metal layer, the second imaged metal layer,the third imaged metal layer and the fourth imaged metal layer arecopper.

In some embodiments, the circuit board comprises, in the following order

-   -   a. a first imaged metal layer    -   b. a first electrically insulating layer having a first side and        a second side; the first side of the first electrically        insulating layer is next to the first imaged metal layer and is        derived from 100 mole % 3,3′,4,4′-biphenyl tetracarboxylic        dianhydride, 20 to 90 mole % 2,2′-bis(trifluoromethyl)benzidine,        and 10 to 80 mole % 4,4′-oxydianiline;    -   c. a second imaged metal layer; the second side of the first        electrically insulating layer is next to the second imaged metal        layer;    -   d. a polyimide bondply derived from 100 mole %        3,3′,4,4′-biphenyl tetracarboxylic dianhydride, 20 to 90 mole %        2,2′-bis(trifluoromethyl)benzidine, and 10 to 80 mole %        4,4′-oxydianiline;    -   e. a third imaged metal layer;    -   f. a second electrically insulating layer having a first side        and a second side; the first side of the second electrically        insulating layer is next to the third imaged metal layer and is        derived from 100 mole % 3,3′,4,4′-biphenyl tetracarboxylic        dianhydride, 20 to 90 mole % 2,2′-bis(trifluoromethyl)benzidine,        and 10 to 80 mole % 4,4′-oxydianiline;    -   g. a fourth imaged metal layer; the second side of the second        electrically insulating layer is next to the fourth imaged metal        layer. The polyimide bondply is in direct contact with the        second imaged metal layer and exposed areas of the second side        of the first electrically insulating layer and in direct contact        with the third imaged metal layer and exposed areas of the first        side of the second electrically insulating layer. The polyimide        bondply has a peel strength from 0.7 to 2 N/mm as measured in        accordance with IPC-TM-650-2.4.9d, when    -   i) the first imaged metal layer, the first electrically        insulating layer and the second image metal layer; and    -   ii) the polyimide bondply;    -   iii) the third imaged metal layer, the second electrically        insulating layer and the fourth imaged metal layer are laminated        at a lamination temperature from 300 to 380° C. and a pressure        from 150 psi (10.55 Kg/cm) to 400 psi (28.13 Kg/cm).

In some embodiments, the circuit board comprises, in the followingorder:

-   -   a. a first imaged metal layer    -   b. a first electrically insulating layer having a first side and        a second side; the first side of the first electrically        insulating layer is next to the first imaged metal layer and is        derived from 100 mole % 3,3′,4,4′-biphenyl tetracarboxylic        dianhydride, 40 to 90 mole % 2,2′-bis(trifluoromethyl)benzidine,        and 10 to 60 mole % 4,4′-oxydianiline;    -   c. a second imaged metal layer; the second side of the first        electrically insulating layer is next to the second imaged metal        layer;    -   d. a polyimide bondply derived from 100 mole %        3,3′,4,4′-biphenyl tetracarboxylic dianhydride, 40 to 90 mole %        2,2′-bis(trifluoromethyl)benzidine, and 10 to 60 mole %        4,4′-oxydianiline;    -   e. a third imaged metal layer;    -   f. a second electrically insulating layer having a first side        and a second side; the first side of the second electrically        insulating layer is next to the third imaged metal layer and is        derived from 100 mole % 3,3′,4,4′-biphenyl tetracarboxylic        dianhydride, 40 to 90 mole % 2,2′-bis(trifluoromethyl)benzidine,        and 10 to 60 mole % 4,4′-oxydianiline;    -   g. a fourth imaged metal layer; the second side of the second        electrically insulating layer is next to the fourth imaged metal        layer. The polyimide bondply is in direct contact with the        second imaged metal layer and exposed areas of the second side        of the first electrically insulating layer and in direct contact        with the third imaged metal layer and exposed areas of the first        side of the second electrically insulating layer. The polyimide        bondply has a peel strength from 1 to 2 N/mm as measured in        accordance with IPC-TM-650-2.4.9d, when    -   i) the first imaged metal layer, the first electrically        insulating layer and the second image metal layer; and

ii) the polyimide bondply;

-   -   iii) the third imaged metal layer, the second electrically        insulating layer and the fourth imaged metal layer are laminated        at a lamination temperature from 320 to 380° C. and a pressure        from 150 psi (10.55 Kg/cm) to 400 psi (28.13 Kg/cm).

In some embodiments, the circuit board further comprises an adhesive anda first coverlay wherein the adhesive is between and in direct contactwith the first imaged metal layer and the exposed areas of the firstside of the first electrically insulating layer and the first coverlay.In some embodiments, the circuit board further comprises a secondadhesive and a second coverlay wherein the second adhesive is betweenand in direct contact with the fourth imaged metal layer and the exposedareas of the second side of the second electrically insulating layer andthe second coverlay.

In some embodiments, the circuit board further comprises an adhesive anda first coverlay wherein the adhesive is between and in direct contactwith the first imaged metal layer and the exposed areas of the firstside of the first electrically insulating layer and the first coverlayand a second adhesive and a second coverlay wherein the second adhesiveis between and in direct contact with the fourth imaged layer and theexposed areas of the second side of the second electrically insulatinglayer and the second coverlay.

In one embodiment, the adhesive and the second adhesive can be anytraditional adhesive used to bond a coverlay to an imaged metal layerwhen the coverlay is added after the circuit board is formed. Thecircuit board can have any number of imaged metal layers andelectrically insulating layers. In some embodiments, two imaged metallayers separated by an electrically insulating layer can be called aclad or metal clad. And number of these clads can be adhered to eachother via the polyimide bondply of the present disclosure.

In another embodiment, the circuit board, comprises in the followingorder

-   -   a. a first polyimide coverlay derived from 100 mole %        3,3′,4,4′-biphenyl tetracarboxylic dianhydride, 20 to 90 mole %        2,2′-bis(trifluoromethyl)benzidine, and 10 to 80 mole %        4,4′-oxydianiline;    -   b. a first imaged metal layer    -   c. a first electrically insulating layer having a first side and        a second side; the first side of the first electrically        insulating layer is next to the first imaged metal layer    -   d. a second imaged metal layer; the second side of the first        electrically insulating layer is next to the second imaged metal        layer;    -   e. a polyimide bondply derived from 100 mole %        3,3′,4,4′-biphenyl tetracarboxylic dianhydride, 20 to 90 mole %        2,2′-bis(trifluoromethyl)benzidine, and 10 to 80 mole %        4,4′-oxydianiline;    -   f. a third imaged metal layer;    -   g. a second electrically insulating layer having a first side        and a second side; the first side of the second electrically        insulating layer is next to the third imaged metal layer    -   h. a fourth imaged metal layer; the second side of the second        electrically insulating layer is next to the fourth imaged metal        layer;    -   i. a second polyimide coverlay derived from 100 mole %        3,3′,4,4′-biphenyl tetracarboxylic dianhydride, 20 to 90 mole %        2,2′-bis(trifluoromethyl)benzidine, and 10 to 80 mole %        4,4′-oxydianiline. The polyimide bondply is in direct contact        with the second imaged metal layer and exposed areas of the        second side of the first electrically insulating layer and in        direct contact with the third imaged metal layer and exposed        areas of the first side of the second electrically insulating        layer. The polyimide bondply has a peel strength from 0.7 to 2        N/mm as measured in accordance with IPC-TM-650-2.4.9d, when    -   i) the first imaged metal layer, the first electrically        insulating layer and the second image metal layer;    -   ii) the polyimide bondply;    -   iii) the third imaged metal layer, the second electrically        insulating layer and the fourth imaged metal layer are laminated        at a lamination temperature from 300 to 380° C. and a pressure        from 150 psi (10.55 Kg/cm) to 400 psi (28.13 Kg/cm). The first        polyimide coverlay is in direct contact with the first imaged        metal layer and exposed areas of the first side of the first        electrically insulating layer and wherein the second polyimide        coverlay is in direct contact with the fourth imaged metal layer        and exposed areas of the second side of the second electrically        insulating layer and the first electrically insulating layer and        the second electrically insulating layer are any electrically        insulating material that can withstand the lamination        temperature from 300 to 380° C.

In another embodiment, the circuit board, comprises in the followingorder:

-   -   a. a first polyimide coverlay derived from 100 mole %        3,3′,4,4′-biphenyl tetracarboxylic dianhydride, 40 to 90 mole %        2,2′-bis(trifluoromethyl)benzidine, and 10 to 60 mole %        4,4′-oxydianiline;    -   b. a first imaged metal layer    -   c. a first electrically insulating layer having a first side and        a second side; the first side of the first electrically        insulating layer is next to the first imaged metal layer    -   d. a second imaged metal layer; the second side of the first        electrically insulating layer is next to the second imaged metal        layer    -   e. a polyimide bondply derived from 100 mole %        3,3′,4,4′-biphenyl tetracarboxylic dianhydride, 40 to 90 mole %        2,2′-bis(trifluoromethyl)benzidine, and 10 to 60 mole %        4,4′-oxydianiline;    -   f. a third imaged metal layer;    -   g. a second electrically insulating layer having a first side        and a second side; the first side of the second electrically        insulating layer is next to the third imaged metal layer    -   h. a fourth imaged metal layer; the second side of the second        electrically insulating layer is next to the fourth imaged metal        layer;    -   i. a second polyimide coverlay derived from 100 mole %        3,3′,4,4′-biphenyl tetracarboxylic dianhydride, 40 to 90 mole %        2,2′-bis(trifluoromethyl)benzidine, and 10 to 60 mole %        4,4′-oxydianiline. The polyimide bondply is in direct contact        with the second imaged metal layer and exposed areas of the        second side of the first electrically insulating layer; and in        direct contact with the third imaged metal layer and exposed        areas of the first side of the second electrically insulating        layer. The polyimide bondply has a peel strength from 1 to 2        N/mm as measured in accordance with IPC-TM-650-2.4.9d, when    -   i) the first imaged metal layer, the first electrically        insulating layer and the second image metal layer;    -   ii) the polyimide bondply;    -   iii) the third imaged metal layer, the second electrically        insulating layer and the fourth imaged metal layer are laminated        at a lamination temperature from 320 to 380° C. and a pressure        from 150 psi (10.55 Kg/cm) to 400 psi (28.13 Kg/cm).

The first polyimide coverlay is in direct contact with the first imagedmetal layer and exposed areas of the first side of the firstelectrically insulating layer and wherein the second polyimide coverlayis in direct contact with the fourth imaged metal layer and exposedareas of the second side of the second electrically insulating layer andthe first electrically insulating layer and the second electricallyinsulating layer are any electrically insulating material that canwithstand the lamination temperature from 320 to 380° C.

In another embodiment, the circuit board, comprising in the followingorder:

-   -   a. a first polyimide coverlay derived from 100 mole %        3,3′,4,4′-biphenyl tetracarboxylic dianhydride, 40 to 90 mole %        2,2′-bis(trifluoromethyl)benzidine, and 10 to 60 mole %        4,4′-oxydianiline;    -   b. a first imaged copper layer    -   c. a first electrically insulating layer having a first side and        a second side; the first side of the first electrically        insulating layer is next to the first imaged copper layer    -   d. a second imaged copper layer; the second side of the first        electrically insulating layer is next to the second imaged        copper layer;    -   e. a polyimide bondply derived from 100 mole %        3,3′,4,4′-biphenyl tetracarboxylic dianhydride, 40 to 90 mole %        2,2′-bis(trifluoromethyl)benzidine, and 10 to 60 mole %        4,4′-oxydianiline;    -   f. a third imaged copper layer;    -   g. a second electrically insulating layer having a first side        and a second side; the first side of the second electrically        insulating layer is next to the third imaged copper layer    -   h. a fourth imaged copper layer; the second side of the second        electrically insulating layer is next to the fourth imaged        copper layer;    -   i. a second polyimide coverlay derived from 100 mole %        3,3′,4,4′-biphenyl tetracarboxylic dianhydride, 40 to 90 mole %        2,2′-bis(trifluoromethyl)benzidine, and 10 to 60 mole %        4,4′-oxydianiline. The polyimide bondply is in direct contact        with the second imaged copper layer and exposed areas of the        second side of the first electrically insulating layer; and in        direct contact with the third imaged copper layer and exposed        areas of the first side of the second electrically insulating        layer.

In another embodiment, the circuit board, comprising in the followingorder:

-   -   a. a first polyimide coverlay derived from 100 mole %        3,3′,4,4′-biphenyl tetracarboxylic dianhydride, 20 to 90 mole %        2,2′-bis(trifluoromethyl)benzidine, and 10 to 80 mole %        4,4′-oxydianiline;    -   b. a first imaged metal layer    -   c. a first electrically insulating layer having a first side and        a second side; the first side of the first electrically        insulating layer is next to the first imaged metal layer and is        derived from 100 mole % 3,3′,4,4′-biphenyl tetracarboxylic        dianhydride, 20 to 90 mole % 2,2′-bis(trifluoromethyl)benzidine,        and 10 to 80 mole % 4,4′-oxydianiline;    -   d. a second imaged metal layer; the second side of the first        electrically insulating layer is next to the second imaged metal        layer;    -   e. a polyimide bondply derived from 100 mole %        3,3′,4,4′-biphenyl tetracarboxylic dianhydride, 20 to 90 mole %        2,2′-bis(trifluoromethyl)benzidine, and 10 to 80 mole %        4,4′-oxydianiline;    -   f. a third imaged metal layer;    -   g. a second electrically insulating layer having a first side        and a second side; the first side of the second electrically        insulating layer is next to the third imaged metal layer and is        derived from 100 mole % 3,3′,4,4′-biphenyl tetracarboxylic        dianhydride, 20 to 90 mole % 2,2′-bis(trifluoromethyl)benzidine,        and 10 to 80 mole % 4,4′-oxydianiline    -   h. a fourth imaged metal layer; the second side of the second        electrically insulating layer is next to the fourth imaged metal        layer;    -   i. a second polyimide coverlay derived from 100 mole %        3,3′,4,4′-biphenyl tetracarboxylic dianhydride, 20 to 90 mole %        2,2′-bis(trifluoromethyl)benzidine, and 10 to 80 mole %        4,4′-oxydianiline. The polyimide bondply is in direct contact        with the 15 second imaged metal layer and exposed areas of the        second side of the first electrically insulating layer; and in        direct contact with the third imaged metal layer and exposed        areas of the first side of the second electrically insulating        layer. The polyimide bondply has a peel strength from 0.7 to 2        N/mm as measured in accordance with IPC-TM-650-2.4.9d, when    -   i) the first imaged metal layer, the first electrically        insulating layer and the second image metal layer;    -   ii) the polyimide bondply;    -   iii) the third imaged metal layer, the second electrically        insulating layer and the fourth imaged metal layer are laminated        at a lamination temperature from 300 to 380° C. and a pressure        from 150 psi (10.55 Kg/cm) to 400 psi (28.13 Kg/cm).

In another embodiment, the circuit board, comprising in the followingorder:

-   -   a. a first polyimide coverlay derived from 100 mole %        3,3′,4,4′-biphenyl tetracarboxylic dianhydride, 40 to 90 mole %        2,2′-bis(trifluoromethyl)benzidine, and 10 to 60 mole %        4,4′-oxydianiline;    -   b. a first imaged metal layer    -   c. a first electrically insulating layer having a first side and        a second side; the first side of the first electrically        insulating layer is next to the first imaged metal layer and is        derived from 100 mole % 3,3′,4,4′-biphenyl tetracarboxylic        dianhydride, 40 to 90 mole % 2,2′-bis(trifluoromethyl)benzidine,        and 10 to 60 mole % 4,4′-oxydianiline;    -   d. a second imaged metal layer; the second side of the first        electrically insulating layer is next to the second imaged metal        layer    -   e. a polyimide bondply derived from 100 mole %        3,3′,4,4′-biphenyl tetracarboxylic dianhydride, 40 to 90 mole %        2,2′-bis(trifluoromethyl)benzidine, and 10 to 60 mole %        4,4′-oxydianiline;    -   f. a third imaged metal layer;    -   g. a second electrically insulating layer having a first side        and a second side; the first side of the second electrically        insulating layer is next to the third imaged metal layer and is        derived from 100 mole % 3,3′,4,4′-biphenyl tetracarboxylic        dianhydride, 40 to 90 mole % 2,2′-bis(trifluoromethyl)benzidine,        and 10 to 60 mole % 4,4′-oxydianiline    -   h. a fourth imaged metal layer, the second side of the second        electrically insulating layer is next to the fourth imaged metal        layer;    -   i. a second polyimide coverlay derived from 100 mole %        3,3′,4,4′-biphenyl tetracarboxylic dianhydride, 40 to 90 mole %        2,2′-bis(trifluoromethyl)benzidine, and 10 to 60 mole %        4,4′-oxydianiline. The polyimide bondply is in direct contact        with the second imaged metal layer and exposed areas of the        second side of the first electrically insulating layer and in        direct contact with the third imaged metal layer and exposed        areas of the first side of the second electrically insulating        layer. The polyimide bondply has a peel strength from 1 to 2        N/mm as measured in accordance with IPC-TM-650-2.4.9d, when    -   i) the first imaged metal layer, the first electrically        insulating layer and the second image metal layer,    -   ii) the polyimide bondply;    -   iii) the third imaged metal layer, the second electrically        insulating layer and the fourth imaged metal layer are laminated        at a lamination temperature from 320 to 380° C. and a pressure        from 150 psi (10.55 Kg/cm) to 400 psi (28.13 Kg/cm).

In another embodiment, the circuit board, comprising in the followingorder:

-   -   a. a first polyimide coverlay derived from 100 mole %        3,3′,4,4′-biphenyl tetracarboxylic dianhydride, 20 to 30 mole %        2,2′-bis(trifluoromethyl)benzidine, and 70 to 80 mole %        4,4′-oxydianiline;    -   b. a first imaged metal layer    -   c. a first electrically insulating layer having a first side and        a second side; the first side of the first electrically        insulating layer is next to the first imaged metal layer and is        derived from 100 mole % 3,3′,4,4′-biphenyl tetracarboxylic        dianhydride, 20 to 30 mole % 2,2′-bis(trifluoromethyl)benzidine,        and 70 to 80 mole % 4,4′-oxydianiline;    -   d. a second imaged metal layer; the second side of the first        electrically insulating layer is next to the second imaged metal        layer;    -   e. a polyimide bondply derived from 100 mole %        3,3′,4,4′-biphenyl tetracarboxylic dianhydride, 20 to 30 mole %        2,2′-bis(trifluoromethyl)benzidine, and 70 to 80 mole %        4,4′-oxydianiline;    -   f. a third imaged metal layer;    -   g. a second electrically insulating layer having a first side        and a second side; the first side of the second electrically        insulating layer is next to the third imaged metal layer and is        derived from 100 mole % 3,3′,4,4′-biphenyl tetracarboxylic        dianhydride, 20 to 30 mole % 2,2′-bis(trifluoromethyl)benzidine,        and 70 to 80 mole % 4,4′-oxydianiline    -   h. a fourth imaged metal layer; the second side of the second        electrically insulating layer is next to the fourth imaged metal        layer;    -   i. a second polyimide coverlay derived from 100 mole %        3,3′,4,4′-biphenyl tetracarboxylic dianhydride, 20 to 30 mole %        2,2′-bis(trifluoromethyl)benzidine, and 70 to 80 mole %        4,4′-oxydianiline. The polyimide bondply is in direct contact        with the second imaged metal layer and exposed areas of the        second side of the first electrically insulating layer and in        direct contact with the third imaged metal layer and exposed        areas of the first side of the second electrically insulating        layer. The polyimide bondply has a peel strength from 0.7 to 2        N/mm as measured in accordance with IPC-TM-650-2.4.9d, when    -   i) the first imaged metal layer, the first electrically        insulating layer and the second image metal layer    -   ii) the polyimide bondply;    -   iii) the third imaged metal layer, the second electrically        insulating layer and the fourth imaged metal layer are laminated        at a lamination temperature from 300 to 380° C. and a pressure        from 150 psi (10.55 Kg/cm) to 400 psi (28.13 Kg/cm).

In some embodiments it is desirable to have a coverlay with a matteappearance. Polymeric materials typically have inherent surface gloss.To control gloss (and thereby produce matte surface characteristics)various additive approaches are possible to achieve dull and low glosssurface characteristics.

Silicas are inorganic particles that can be ground and filtered tospecific particle size ranges. The very irregular shape and porosity ofsilica particles and low cost make it a popular matting agent. Otherpotential matting agents can include: i. other ceramics, such as,borides, nitrides, carbides and other oxides (e.g., alumina, titania,etc); and ii. organic particles. In some embodiments, the organicparticles must withstand the high temperature processing of a chemicallyconverted polyimide (processing temperatures of from about 250° C. toabout 550° C., depending upon the particular polyimide process chosen)when the coverlay is a polyimide coverlay. One organic matting agentthat can withstand the thermal conditions of polyimide synthesis arepolyimide particles. In some embodiments, the matting agent is polyimideparticles. In some embodiments, the first polyimide coverlay comprisespolyimide particles. In some embodiments, the second polyimide coverlaycomprises polyimide particles. In some embodiments, both the firstpolyimide coverlay and the second polyimide coverlay comprise polyimideparticles.

The amount of matting agent, median particle size and density must besufficient to produce the desired 60 degree gloss value. In someembodiments, the 60 degree gloss value is between and optionallyincluding any two of the following: 2, 5, 10, 15, 20, 25, 30 and 35. Insome embodiments, the 60 degree gloss value is from 10 to 35. In someembodiments, the 60 degree gloss value is from 2 to 25. The 60 degreegloss value is measured using Micro-TRI Gloss gloss meter.

In some embodiments, the first polyimide coverlay and the secondpolyimide coverlay independently comprise, a matting agent present in anamount between and optionally including any two of the following: 1.6,2, 3, 4, 5, 6, 7, 8, 9 and 10 weight percent of polyimide coverlay. Insome embodiments, the matting agent has a median particle size betweenand optionally including any two of the following: 1.3, 2, 3, 4, 5, 6,7, 8, 9 and 10 microns. The matting agent particles should have anaverage particle size of less than (or equal to) about 10 microns andgreater than (or equal to) about 1.3 microns. Larger matting agentparticles may negatively impact mechanical properties. In someembodiments, the matting agent has a density between and optionallyincluding any two of the following: 2, 3, 4 and 4.5 g/cc. In someembodiments, the matting agent is selected from the group consisting ofsilica, alumina, barium sulfate and mixtures thereof.

In some embodiments, the first polyimide coverlay comprises a pigmentand a matting agent. In some embodiments, the second polyimide coverlaycomprises a pigment and a matting agent. In some embodiments the firstpolyimide coverlay, the second polyimide coverlay or both comprise apigment and a matting agent.

In some embodiments, the pigment and the matting agent are both a lowconductivity carbon black and in such embodiments, the low conductivitycarbon black is present in the first polyimide coverlay in an amountfrom 2 to 20 weight percent.

In some embodiments, the pigment and the matting agent are both a lowconductivity carbon black and in such embodiments, the low conductivitycarbon black is present in the first polyimide coverlay in an amountbetween and including any two of the following: 2, 5, 10, 15 and 20weight percent.

In some embodiments, the pigment and the matting agent are both a lowconductivity carbon black and in such embodiments, the low conductivitycarbon black is present in the second polyimide coverlay in an amountbetween and including any two of the following: 2, 5, 10, 15 and 20weight percent.

In some embodiments, the pigment and the matting agent in both the firstpolyimide coverlay and the second polyimide coverlay are a lowconductivity carbon black and the low conductivity carbon black ispresent in the first polyimide coverlay in an amount from 2 to 20 weightpercent and the low conductivity carbon black is present in the secondpolyimide coverlay in an amount from 2 to 20 weight percent.

In some embodiments, the pigment and the matting agent are both a lowconductivity carbon black and the low conductivity carbon black ispresent in the first polyimide coverlay, the second polyimide coverlayor both in an amount from 2 to 20 weight percent.

In another embodiment, the matting agent is polyimide particles.

In another embodiment, the first polyimide coverlay, the secondpolyimide coverlay or both comprise a low conductivity carbon black anda matting agent.

In some embodiments, the pigment and the matting agent are both a lowconductivity carbon black and in such embodiments, the low conductivitycarbon black is present in the first polyimide coverlay in an amountbetween and including any two of the following: 2, 5, 10, 15 and 20weight percent.

In some embodiments, the first polyimide coverlay comprises a lowconductivity carbon black present in an amount from 2 to 9 weightpercent and the second polyimide coverlay comprises a non-carbon blackpigment present in an amount from 10 to 60 weight percent.

In another embodiment, the first polyimide coverlay comprises a lowconductivity carbon black present in an amount from 2 to 9 weightpercent and the second polyimide coverlay comprises a pigment and amatting agent. In another embodiment, the pigment and the matting agentin the second polyimide coverlay are both a low conductivity carbonblack, the carbon black present in an amount from 2 to 20 weightpercent.

In another embodiment, the first polyimide coverlay comprises a lowconductivity carbon black present in an amount from 2 to 9 weightpercent and the second polyimide coverlay comprises a pigment and amatting agent, and wherein the matting agent is polyimide particles.

In another embodiment, the circuit board, comprises in the followingorder:

-   -   a. a first polyimide coverlay derived from 100 mole %        3,3′,4,4′-biphenyl tetracarboxylic dianhydride, 40 to 90 mole %        2,2′-bis(trifluoromethyl)benzidine, and 10 to 60 mole %        4,4′-oxydianiline;    -   b. a first imaged metal layer    -   c. a first electrically insulating layer having a first side and        a second side; the first side of the first electrically        insulating layer is next to the first imaged metal layer    -   d. a second imaged metal layer; the second side of the first        electrically insulating layer is next to the second imaged metal        layer,    -   e. a polyimide bondply derived from 100 mole %        3,3′,4,4′-biphenyl tetracarboxylic dianhydride, 40 to 90 mole %        2,2′-bis(trifluoromethyl)benzidine, and 10 to 60 mole %        4,4′-oxydianiline;    -   f. a third imaged metal layer;    -   g. a second electrically insulating layer having a first side        and a second side; the first side of the second electrically        insulating layer is next to the third imaged metal layer    -   h. a fourth imaged metal layer, the second side of the second        electrically insulating layer is next to the fourth imaged metal        layer;    -   i. a second polyimide coverlay derived from 100 mole %        3,3′,4,4′-biphenyl tetracarboxylic dianhydride, 40 to 90 mole %        2,2′-bis(trifluoromethyl)benzidine, and 10 to 60 mole %        4,4′-oxydianiline. The polyimide bondply is in direct contact        with the second imaged metal layer and exposed areas of the        second side of the first electrically insulating layer; and in        direct contact with the third imaged metal layer and exposed        areas of the first side of the second electrically insulating        layer. The polyimide bondply has a peel strength from 1 to 2        N/mm as measured in accordance with IPC-TM-650-2.4.9d, when    -   i) the first imaged metal layer, the first electrically        insulating layer and the second image metal layer;    -   ii) the polyimide bondply;    -   iii) the third imaged metal layer, the second electrically        insulating layer and the fourth imaged metal layer are laminated        at a lamination temperature from 320 to 380° C. and a pressure        from 150 psi (10.55 Kg/cm) to 400 psi (28.13 Kg/cm). The first        polyimide coverlay is in direct contact with the first imaged        metal layer and exposed areas of the first side of the first        electrically insulating layer and wherein the second polyimide        coverlay is in direct contact with the fourth imaged metal layer        and exposed areas of the second side of the second electrically        insulating layer and the first electrically insulating layer and        the second electrically insulating layer are any electrically        insulating material that can withstand the lamination        temperature from 320 to 380° C. The first polyimide coverlay,        the second polyimide coverlay or both comprise a pigment and a        matting agent.

In yet another embodiment, the circuit board, comprises in the followingorder:

-   -   a. a first polyimide coverlay derived from 100 mole %        3,3′,4,4′-biphenyl tetracarboxylic dianhydride, 40 to 90 mole %        2,2′-bis(trifluoromethyl)benzidine, and 10 to 60 mole %        4,4′-oxydianiline;    -   b. a first imaged metal layer    -   c. a first electrically insulating layer having a first side and        a second side; the first side of the first electrically        insulating layer is next to the first imaged metal layer    -   d. a second imaged metal layer, the second side of the first        electrically insulating layer is next to the second imaged metal        layer;    -   e. a polyimide bondply derived from 100 mole %        3.3′,4,4′-biphenyl tetracarboxylic dianhydride, 40 to 90 mole %        2,2′-bis(trifluoromethyl)benzidine, and 10 to 60 mole %        4,4′-oxydianiline;    -   f. a third imaged metal layer;    -   g. a second electrically insulating layer having a first side        and a second side; the first side of the second electrically        insulating layer is next to the third imaged metal layer    -   h. a fourth imaged metal layer; the second side of the second        electrically insulating layer is next to the fourth imaged metal        layer;    -   i. a second polyimide coverlay derived from 100 mole %        3,3′,4,4′-biphenyl tetracarboxylic dianhydride, 40 to 90 mole %        2,2′-bis(trifluoromethyl)benzidine, and 10 to 60 mole %        4,4′-oxydianiline. The polyimide bondply is in direct contact        with the second imaged metal layer and exposed areas of the        second side of the first electrically insulating layer; and in        direct contact with the third imaged metal layer and exposed        areas of the first side of the second electrically insulating        layer. The polyimide bondply has a peel strength from 1 to 2        N/mm as measured in accordance with IPC-TM-650-2.4.9d, when    -   i) the first imaged metal layer, the first electrically        insulating layer and the second image metal layer;    -   ii) the polyimide bondply;    -   iii) the third imaged metal layer, the second electrically        insulating layer and the fourth imaged metal layer are laminated        at a lamination temperature from 320 to 380° C. and a pressure        from 150 psi (10.55 Kg/cm) to 400 psi (28.13 Kg/cm). The first        polyimide coverlay is in direct contact with the first imaged        metal layer and exposed areas of the first side of the first        electrically insulating layer and wherein the second polyimide        coverlay is in direct contact with the fourth imaged metal layer        and exposed areas of the second side of the second electrically        insulating layer and the first electrically insulating layer and        the second electrically insulating layer are any electrically        insulating material that can withstand the lamination        temperature from 320 to 380° C. The first polyimide coverlay,        the second polyimide coverlay or both comprise a low        conductivity carbon black and a matting agent.

In yet another embodiment, the circuit board, comprises in the followingorder:

-   -   a. a first polyimide coverlay derived from 100 mole %        3,3′,4,4′-biphenyl tetracarboxylic dianhydride, 40 to 90 mole %        2,2′-bis(trifluoromethyl)benzidine, and 10 to 60 mole %        4,4′-oxydianiline;    -   b. a first imaged metal layer    -   c. a first electrically insulating layer having a first side and        a second side; the first side of the first electrically        insulating layer is next to the first imaged metal layer    -   d. a second imaged metal layer; the second side of the first        electrically insulating layer is next to the second imaged metal        layer;    -   e. a polyimide bondply derived from 100 mole %        3,3′,4,4′-biphenyl tetracarboxylic dianhydride, 40 to 90 mole %        2,2′-bis(trifluoromethyl)benzidine, and 10 to 60 mole %        4,4′-oxydianiline;    -   f. a third imaged metal layer;    -   g. a second electrically insulating layer having a first side        and a second side; the first side of the second electrically        insulating layer is next to the third imaged metal layer    -   h. a fourth imaged metal layer; the second side of the second        electrically insulating layer is next to the fourth imaged metal        layer;    -   i. a second polyimide coverlay derived from 100 mole %        3,3′,4,4′-biphenyl tetracarboxylic dianhydride, 40 to 90 mole %        2,2′-bis(trifluoromethyl)benzidine, and 10 to 60 mole %        4,4′-oxydianiline. The polyimide bondply is in direct contact        with the second imaged metal layer and exposed areas of the        second side of the first electrically insulating layer; and in        direct contact with the third imaged metal layer and exposed        areas of the first side of the second electrically insulating        layer. The polyimide bondply has a peel strength from 1 to 2        N/mm as measured in accordance with IPC-TM-650-2.4.9d, when    -   i) the first imaged metal layer, the first electrically        insulating layer and the second image metal layer;    -   ii) the polyimide bondply;    -   iii) the third imaged metal layer, the second electrically        insulating layer and the fourth imaged metal layer are laminated        at a lamination temperature from 320 to 380° C. and a pressure        from 150 psi (10.55 Kg/cm) to 400 psi (28.13 Kg/cm). The first        polyimide coverlay is in direct contact with the first imaged        metal layer and exposed areas of the first side of the first        electrically insulating layer and wherein the second polyimide        coverlay is in direct contact with the fourth imaged metal layer        and exposed areas of the second side of the second electrically        insulating layer and the first electrically insulating layer and        the second electrically insulating layer are any electrically        insulating material that can withstand the lamination        temperature from 320 to 380° C. And wherein the first polyimide        coverlay, the second polyimide coverlay or both comprise a        pigment and a matting agent and wherein the pigment and the        matting agent are both a low conductivity carbon black and the        low conductivity carbon black is present in the first polyimide        coverlay, the second polyimide coverlay or both in an amount        from 2 to 20 weight percent.

In another embodiment, the circuit board, comprises in the followingorder:

-   -   a. a first polyimide coverlay derived from 100 mole %        3,3′,4,4′-biphenyl tetracarboxylic dianhydride, 40 to 90 mole %        2,2′-bis(trifluoromethyl)benzidine, and 10 to 60 mole %        4,4′-oxydianiline;    -   b. a first imaged metal layer    -   c. a first electrically insulating layer having a first side and        a second side; the first side of the first electrically        insulating layer is next to the first imaged metal layer    -   d. a second imaged metal layer, the second side of the first        electrically insulating layer is next to the second imaged metal        layer;    -   e. a polyimide bondply derived from 100 mole %        3,3′,4,4′-biphenyl tetracarboxylic dianhydride, 40 to 90 mole %        2,2′-bis(trifluoromethyl)benzidine, and 10 to 60 mole %        4,4′-oxydianiline;    -   f. a third imaged metal layer;    -   g. a second electrically insulating layer having a first side        and a second side; the first side of the second electrically        insulating layer is next to the third imaged metal layer    -   h. a fourth imaged metal layer, the second side of the second        electrically insulating layer is next to the fourth imaged metal        layer;    -   i. a second polyimide coverlay derived from 100 mole %        3,3′,4,4′-biphenyl tetracarboxylic dianhydride, 40 to 90 mole %        2,2′-bis(trifluoromethyl)benzidine, and 10 to 60 mole %        4,4′-oxydianiline. The polyimide bondply is in direct contact        with the second imaged metal layer and exposed areas of the        second side of the first electrically insulating layer; and in        direct contact with the third imaged metal layer and exposed        areas of the first side of the second electrically insulating        layer. The polyimide bondply has a peel strength from 1 to 2        N/mm as measured in accordance with IPC-TM-650-2.4.9d, when    -   i) the first imaged metal layer, the first electrically        insulating layer and the second image metal layer;    -   ii) the polyimide bondply;    -   iii) the third imaged metal layer, the second electrically        insulating layer and the fourth imaged metal layer are laminated        at a lamination temperature from 320 to 380° C. and a pressure        from 150 psi (10.55 Kg/cm) to 400 psi (28.13 Kg/cm). The first        polyimide coverlay is in direct contact with the first imaged        metal layer and exposed areas of the first side of the first        electrically insulating layer and wherein the second polyimide        coverlay is in direct contact with the fourth imaged metal layer        and exposed areas of the second side of the second electrically        insulating layer and the first electrically insulating layer and        the second electrically insulating layer are any electrically        insulating material that can withstand the lamination        temperature from 320 to 380° C. And wherein the first polyimide        coverlay, the second polyimide coverlay or both comprise a        pigment and a matting agent and wherein the matting agent is        polyimide particles.

In another embodiment, the circuit board, comprising in the followingorder:

-   -   a. a first polyimide coverlay derived from 100 mole %        3,3′,4,4′-biphenyl tetracarboxylic dianhydride, 40 to 90 mole %        2,2′-bis(trifluoromethyl)benzidine, and 10 to 60 mole %        4,4′-oxydianiline;    -   b. a first imaged metal layer    -   c. a first electrically insulating layer having a first side and        a second side; the first side of the first electrically        insulating layer is next to the first imaged metal layer and is        derived from 100 mole % 3,3′,4,4′-biphenyl tetracarboxylic        dianhydride, 40 to 90 mole % 2,2′-bis(trifluoromethyl)benzidine,        and 10 to 60 mole % 4,4′-oxydianiline;    -   d. a second imaged metal layer; the second side of the first        electrically insulating layer is next to the second imaged metal        layer;    -   e. a polyimide bondply derived from 100 mole %        3,3′,4,4′-biphenyl tetracarboxylic dianhydride, 40 to 90 mole %        2,2′-bis(trifluoromethyl)benzidine, and 10 to 60 mole %        4,4′-oxydianiline;    -   f. a third imaged metal layer;    -   g. a second electrically insulating layer having a first side        and a second side; the first side of the second electrically        insulating layer is next to the third imaged metal layer and is        derived from 100 mole % 3,3′,4,4′-biphenyl tetracarboxylic        dianhydride, 40 to 90 mole % 2,2′-bis(trifluoromethyl)benzidine,        and 10 to 60 mole % 4,4′-oxydianiline    -   h. a fourth imaged metal layer, the second side of the second        electrically insulating layer is next to the fourth imaged metal        layer;    -   i. a second polyimide coverlay derived from 100 mole %        3,3′,4,4′-biphenyl tetracarboxylic dianhydride, 40 to 90 mole %        2,2′-bis(trifluoromethyl)benzidine, and 10 to 60 mole %        4,4′-oxydianiline. The polyimide bondply is in direct contact        with the second imaged metal layer and exposed areas of the        second side of the first electrically insulating layer; and in        direct contact with the third imaged metal layer and exposed        areas of the first side of the second electrically insulating        layer. The polyimide bondply has a peel strength from 1 to 2        N/mm as measured in accordance with IPC-TM-650-2.4.9d, when    -   i) the first imaged metal layer, the first electrically        insulating layer and the second image metal layer;    -   ii) the polyimide bondply;    -   iii) the third imaged metal layer, the second electrically        insulating layer and the fourth imaged metal layer are laminated        at a lamination temperature from 320 to 380° C. and a pressure        from 150 psi (10.55 Kg/cm) to 400 psi (28.13 Kg/cm). The first        polyimide coverlay is in direct contact with the first imaged        metal layer and exposed areas of the first side of the first        electrically insulating layer and wherein the second polyimide        coverlay is in direct contact with the fourth imaged metal layer        and exposed areas of the second side of the second electrically        insulating layer. The first polyimide coverlay, the second        polyimide coverlay or both comprise a pigment and a matting        agent.

In another embodiment, the circuit board, comprising in the followingorder:

-   -   a. a first polyimide coverlay derived from 100 mole %        3,3′,4,4′-biphenyl tetracarboxylic dianhydride, 40 to 90 mole %        2,2′-bis(trifluoromethyl)benzidine, and 10 to 60 mole %        4,4′-oxydianiline;    -   b. a first imaged metal layer    -   c. a first electrically insulating layer having a first side and        a second side; the first side of the first electrically        insulating layer is next to the first imaged metal layer and is        derived from 100 mole % 3.3′,4,4′-biphenyl tetracarboxylic        dianhydride, 40 to 90 mole % 2,2′-bis(trifluoromethyl)benzidine,        and 10 to 60 mole % 4,4′-oxydianiline;    -   d. a second imaged metal layer; the second side of the first        electrically insulating layer is next to the second imaged metal        layer,    -   e. a polyimide bondply derived from 100 mole %        3,3′,4,4′-biphenyl tetracarboxylic dianhydride, 40 to 90 mole %        2,2′-bis(trifluoromethyl)benzidine, and 10 to 60 mole %        4,4′-oxydianiline;    -   f. a third imaged metal layer;    -   g. a second electrically insulating layer having a first side        and a second side; the first side of the second electrically        insulating layer is next to the third imaged metal layer and is        derived from 100 mole % 3,3′,4,4′-biphenyl tetracarboxylic        dianhydride, 40 to 90 mole % 2,2′-bis(trifluoromethyl)benzidine,        and 10 to 60 mole % 4,4′-oxydianiline    -   h. a fourth imaged metal layer; the second side of the second        electrically insulating layer is next to the fourth imaged metal        layer;    -   i. a second polyimide coverlay derived from 100 mole %        3,3′,4,4′-biphenyl tetracarboxylic dianhydride, 40 to 90 mole %        2,2′-bis(trifluoromethyl)benzidine, and 10 to 60 mole %        4,4′-oxydianiline. The polyimide bondply is in direct contact        with the second imaged metal layer and exposed areas of the        second side of the first electrically insulating layer; and in        direct contact with the third imaged metal layer and exposed        areas of the first side of the second electrically insulating        layer. The polyimide bondply has a peel strength from 1 to 2        N/mm as measured in accordance with IPC-TM-650-2.4.9d, when    -   i) the first imaged metal layer, the first electrically        insulating layer and the second image metal layer;    -   ii) the polyimide bondply;    -   iii) the third imaged metal layer, the second electrically        insulating layer and the fourth imaged metal layer are laminated        at a lamination temperature from 320 to 380° C. and a pressure        from 150 psi (10.55 Kg/cm) to 400 psi (28.13 Kg/cm). The first        polyimide coverlay is in direct contact with the first imaged        metal layer and exposed areas of the first side of the first        electrically insulating layer and wherein the second polyimide        coverlay is in direct contact with the fourth imaged metal layer        and exposed areas of the second side of the second electrically        insulating layer. The first polyimide coverlay, the second        polyimide coverlay or both comprise a low conductivity carbon        black and a matting agent.

In another embodiment, the circuit board, comprising in the followingorder:

-   -   a. a first polyimide coverlay derived from 100 mole %        3,3′,4,4′-biphenyl tetracarboxylic dianhydride, 40 to 90 mole %        2,2′-bis(trifluoromethyl)benzidine, and 10 to 60 mole %        4,4′-oxydianiline;    -   b. a first imaged metal layer    -   c. a first electrically insulating layer having a first side and        a second side; the first side of the first electrically        insulating layer is next to the first imaged metal layer and is        derived from 100 mole % 3,3′,4,4′-biphenyl tetracarboxylic        dianhydride, 40 to 90 mole % 2,2′-bis(trifluoromethyl)benzidine,        and 10 to 60 mole % 4,4′-oxydianiline;    -   d. a second imaged metal layer; the second side of the first        electrically insulating layer is next to the second imaged metal        layer    -   e. a polyimide bondply derived from 100 mole %        3,3′,4,4′-biphenyl tetracarboxylic dianhydride, 40 to 90 mole %        2,2′-bis(trifluoromethyl)benzidine, and 10 to 60 mole %        4,4′-oxydianiline;    -   f. a third imaged metal layer;    -   g. a second electrically insulating layer having a first side        and a second side; the first side of the second electrically        insulating layer is next to the third imaged metal layer and is        derived from 100 mole % 3,3′,4,4′-biphenyl tetracarboxylic        dianhydride, 40 to 90 mole % 2,2′-bis(trifluoromethyl)benzidine,        and 10 to 60 mole % 4,4′-oxydianiline    -   h. a fourth imaged metal layer the second side of the second        electrically insulating layer is next to the fourth imaged metal        layer;    -   i. a second polyimide coverlay derived from 100 mole %        3,3′,4,4′-biphenyl tetracarboxylic dianhydride, 40 to 90 mole %        2,2′-bis(trifluoromethyl)benzidine, and 10 to 60 mole %        4,4′-oxydianiline. The polyimide bondply is in direct contact        with the second imaged metal layer and exposed areas of the        second side of the first electrically insulating layer; and in        direct contact with the third imaged metal layer and exposed        areas of the first side of the second electrically insulating        layer. The polyimide bondply has a peel strength from 1 to 2        N/mm as measured in accordance with IPC-TM-650-2.4.9d, when    -   i) the first imaged metal layer, the first electrically        insulating layer and the second image metal layer    -   ii) the polyimide bondply;    -   iii) the third imaged metal layer, the second electrically        insulating layer and the fourth imaged metal layer are laminated        at a lamination temperature from 320 to 380° C. and a pressure        from 150 psi (10.55 Kg/cm) to 400 psi (28.13 Kg/cm). The first        polyimide coverlay is in direct contact with the first imaged        metal layer and exposed areas of the first side of the first        electrically insulating layer and wherein the second polyimide        coverlay is in direct contact with the fourth imaged metal layer        and exposed areas of the second side of the second electrically        insulating layer. And wherein the first polyimide coverlay, the        second polyimide coverlay or both comprise a pigment and a        matting agent and wherein the pigment and the matting agent are        both a low conductivity carbon black and the low conductivity        carbon black is present in the first polyimide coverlay, the        second polyimide coverlay or both in an amount from 2 to 20        weight percent.

In another embodiment, the circuit board, comprising in the followingorder:

-   -   a. a first polyimide coverlay derived from 100 mole %        3,3′,4,4′-biphenyl tetracarboxylic dianhydride, 40 to 90 mole %        2,2′-bis(trifluoromethyl)benzidine, and 10 to 60 mole %        4,4′-oxydianiline;    -   b. a first imaged metal layer    -   c. a first electrically insulating layer having a first side and        a second side; the first side of the first electrically        insulating layer is next to the first imaged metal layer and is        derived from 100 mole % 3,3′,4,4′-biphenyl tetracarboxylic        dianhydride, 40 to 90 mole % 2,2′-bis(trifluoromethyl)benzidine,        and 10 to 60 mole % 4,4′-oxydianiline;    -   d. a second imaged metal layer; the second side of the first        electrically insulating layer is next to the second imaged metal        layer    -   e. a polyimide bondply derived from 100 mole %        3,3′,4,4′-biphenyl tetracarboxylic dianhydride, 40 to 90 mole %        2,2′-bis(trifluoromethyl)benzidine, and 10 to 60 mole %        4,4′-oxydianiline;    -   f. a third imaged metal layer;    -   g. a second electrically insulating layer having a first side        and a second side; the first side of the second electrically        insulating layer is next to the third imaged metal layer and is        derived from 100 mole % 3,3′,4,4′-biphenyl tetracarboxylic        dianhydride, 40 to 90 mole % 2,2′-bis(trifluoromethyl)benzidine,        and 10 to 60 mole % 4,4′-oxydianiline    -   h. a fourth imaged metal layer the second side of the second        electrically insulating layer is next to the fourth imaged metal        layer;    -   i. a second polyimide coverlay derived from 100 mole %        3,3′,4,4′-biphenyl tetracarboxylic dianhydride, 40 to 90 mole %        2,2′-bis(trifluoromethyl)benzidine, and 10 to 60 mole %        4,4′-oxydianiline. The polyimide bondply is in direct contact        with the second imaged metal layer and exposed areas of the        second side of the first electrically insulating layer and in        direct contact with the third imaged metal layer and exposed        areas of the first side of the second electrically insulating        layer. The polyimide bondply has a peel strength from 1 to 2        N/mm as measured in accordance with IPC-TM-650-2.4.9d, when    -   i) the first imaged metal layer, the first electrically        insulating layer and the second image metal layer;    -   ii) the polyimide bondply;    -   iii) the third imaged metal layer, the second electrically        insulating layer and the fourth imaged metal layer are laminated        at a lamination temperature from 320 to 380° C. and a pressure        from 150 psi (10.55 Kg/cm) to 400 psi (28.13 Kg/cm). The first        polyimide coverlay is in direct contact with the first imaged        metal layer and exposed areas of the first side of the first        electrically insulating layer and wherein the second polyimide        coverlay is in direct contact with the fourth imaged metal layer        and exposed areas of the second side of the second electrically        insulating layer. And wherein the first polyimide coverlay, the        second polyimide coverlay or both comprise a pigment and a        matting agent and wherein the matting agent is polyimide        particles.

In yet another embodiment, the circuit board, comprising in thefollowing order

-   -   a. a first polyimide coverlay derived from 100 mole %        3,3′,4,4′-biphenyl tetracarboxylic dianhydride, 40 to 90 mole %        2,2′-bis(trifluoromethyl)benzidine, and 10 to 60 mole %        4,4′-oxydianiline;    -   b. a first imaged copper layer    -   c. a first electrically insulating layer having a first side and        a second side; the first side of the first electrically        insulating layer is next to the first imaged copper layer    -   d. a second imaged copper layer; the second side of the first        electrically insulating layer is next to the second imaged        copper layer    -   e. a polyimide bondply derived from 100 mole %        3,3′,4,4′-biphenyl tetracarboxylic dianhydride, 40 to 90 mole %        2,2′-bis(trifluoromethyl)benzidine, and 10 to 60 mole %        4,4′-oxydianiline;    -   f. a third imaged copper layer;    -   g. a second electrically insulating layer having a first side        and a second side; the first side of the second electrically        insulating layer is next to the third imaged copper layer    -   h. a fourth imaged copper layer the second side of the second        electrically insulating layer is next to the fourth imaged        copper layer    -   i. a second polyimide coverlay derived from 100 mole %        3,3′,4,4′-biphenyl tetracarboxylic dianhydride, 40 to 90 mole %        2,2′-bis(trifluoromethyl)benzidine, and 10 to 60 mole %        4,4′-oxydianiline. The polyimide bondply is in direct contact        with the second imaged copper layer and exposed areas of the        second side of the first electrically insulating layer and in        direct contact with the third imaged copper layer and exposed        areas of the first side of the second electrically insulating        layer. The polyimide bondply has a peel strength from 1 to 2        N/mm as measured in accordance with IPC-TM-650-2.4.9d, when    -   i) the first imaged copper layer, the first electrically        insulating layer and the second imaged copper layer;    -   ii) the polyimide bondply;    -   iii) the third imaged copper layer, the second electrically        insulating layer and the fourth imaged copper layer are        laminated at a lamination temperature from 320 to 380° C. and a        pressure from 150 psi (10.55 Kg/cm) to 400 psi (28.13 Kg/cm).        The first polyimide coverlay is in direct contact with the first        imaged copper layer and exposed areas of the first side of the        first electrically insulating layer and wherein the second        polyimide coverlay is in direct contact with the fourth imaged        copper layer and exposed areas of the second side of the second        electrically insulating layer and wherein the first polyimide        coverlay, the second polyimide coverlay or both comprise a        pigment and a matting agent.

In yet another embodiment, the circuit board, comprising in thefollowing order

-   -   a. a first polyimide coverlay derived from 100 mole %        3,3′,4,4′-biphenyl tetracarboxylic dianhydride, 40 to 90 mole %        2,2′-bis(trifluoromethyl)benzidine, and 10 to 60 mole %        4,4′-oxydianiline;    -   b. a first imaged copper layer    -   c. a first electrically insulating layer having a first side and        a second side; the first side of the first electrically        insulating layer is next to the first imaged copper layer and is        derived from 100 mole % 3,3′,4,4′-biphenyl tetracarboxylic        dianhydride, 40 to 90 mole % 2,2′-bis(trifluoromethyl)benzidine,        and 10 to 60 mole % 4,4′-oxydianiline;    -   d. a second imaged copper layer; the second side of the first        electrically insulating layer is next to the second imaged        copper layer;    -   e. a polyimide bondply derived from 100 mole %        3,3′,4,4′-biphenyl tetracarboxylic dianhydride, 40 to 90 mole %        2,2′-bis(trifluoromethyl)benzidine, and 10 to 60 mole %        4,4′-oxydianiline;    -   f. a third imaged copper layer;    -   g. a second electrically insulating layer having a first side        and a second side; the first side of the second electrically        insulating layer is next to the third imaged copper layer and is        derived from 100 mole % 3,3′,4,4′-biphenyl tetracarboxylic        dianhydride, 40 to 90 mole % 2,2′-bis(trifluoromethyl)benzidine,        and 10 to 60 mole % 4,4′-oxydianiline    -   h. a fourth imaged copper layer; the second side of the second        electrically insulating layer is next to the fourth imaged        copper layer;    -   i. a second polyimide coverlay derived from 100 mole %        3,3′,4,4′-biphenyl tetracarboxylic dianhydride, 40 to 90 mole %        2,2′-bis(trifluoromethyl)benzidine, and 10 to 60 mole %        4,4′-oxydianiline. The polyimide bondply is in direct contact        with the second imaged copper layer and exposed areas of the        second side of the first electrically insulating layer; and in        direct contact with the third imaged copper layer and exposed        areas of the first side of the second electrically insulating        layer. The polyimide bondply has a peel strength from 1 to 2        N/mm as measured in accordance with IPC-TM-650-2.4.9d, when    -   i) the first imaged copper layer, the first electrically        insulating layer and the second imaged copper layer;    -   ii) the polyimide bondply;    -   iii) the third imaged copper layer, the second electrically        insulating layer and the fourth imaged copper layer are        laminated at a lamination temperature from 320 to 380° C. and a        pressure from 150 psi (10.55 Kg/cm) to 400 psi (28.13 Kg/cm).        The first polyimide coverlay is in direct contact with the first        imaged copper layer and exposed areas of the first side of the        first electrically insulating layer and wherein the second        polyimide coverlay is in direct contact with the fourth imaged        copper layer and exposed areas of the second side of the second        electrically insulating layer and wherein the first polyimide        coverlay, the second polyimide coverlay or both comprise a        pigment and a matting agent.

In yet another embodiment, the circuit board, comprising in thefollowing order:

-   -   a. a first polyimide coverlay derived from 100 mole %        3,3′,4,4′-biphenyl tetracarboxylic dianhydride, 40 to 90 mole %        2,2′-bis(trifluoromethyl)benzidine, and 10 to 60 mole %        4,4′-oxydianiline;    -   b. a first imaged copper layer    -   c. a first electrically insulating layer having a first side and        a second side; the first side of the first electrically        insulating layer is next to the first imaged copper layer and is        derived from 100 mole % 3,3′,4,4′-biphenyl tetracarboxylic        dianhydride, 40 to 90 mole % 2,2′-bis(trifluoromethyl)benzidine,        and 10 to 60 mole % 4,4′-oxydianiline;    -   d. a second imaged copper layer; the second side of the first        electrically insulating layer is next to the second imaged        copper layer;    -   e. a polyimide bondply derived from 100 mole %        3.3′,4,4′-biphenyl tetracarboxylic dianhydride, 40 to 90 mole %        2,2′-bis(trifluoromethyl)benzidine, and 10 to 60 mole %        4,4′-oxydianiline;    -   f. a third imaged copper layer;    -   g. a second electrically insulating layer having a first side        and a second side; the first side of the second electrically        insulating layer is next to the third imaged copper layer and is        derived from 100 mole % 3,3′,4,4′-biphenyl tetracarboxylic        dianhydride, 40 to 90 mole % 2,2′-bis(trifluoromethyl)benzidine,        and 10 to 60 mole % 4,4′-oxydianiline    -   h. a fourth imaged copper layer, the second side of the second        electrically insulating layer is next to the fourth imaged        copper layer;    -   i. a second polyimide coverlay derived from 100 mole %        3,3′,4,4′-biphenyl tetracarboxylic dianhydride, 40 to 90 mole %        2,2′-bis(trifluoromethyl)benzidine, and 10 to 60 mole %        4,4′-oxydianiline. The polyimide bondply is in direct contact        with the second imaged copper layer and exposed areas of the        second side of the first electrically insulating layer; and in        direct contact with the third imaged copper layer and exposed        areas of the first side of the second electrically insulating        layer. The polyimide bondply has a peel strength from 1 to 2        N/mm as measured in accordance with IPC-TM-650-2.4.9d, when    -   i) the first imaged copper layer, the first electrically        insulating layer and the second imaged copper layer;    -   ii) the polyimide bondply;    -   iii) the third imaged copper layer, the second electrically        insulating layer and the fourth imaged copper layer are        laminated at a lamination temperature from 320 to 380° C. and a        pressure from 150 psi (10.55 Kg/cm) to 400 psi (28.13 Kg/cm).        The first polyimide coverlay is in direct contact with the first        imaged copper layer and exposed areas of the first side of the        first electrically insulating layer and wherein the second        polyimide coverlay is in direct contact with the fourth imaged        copper layer and exposed areas of the second side of the second        electrically insulating layer and wherein the first polyimide        coverlay, the second polyimide coverlay or both comprise a        pigment and a matting agent and wherein the matting agent is        polyimide particles.

In yet another embodiment, the circuit board, comprising in thefollowing order

-   -   a. a first polyimide coverlay derived from 100 mole %        3,3′,4,4′-biphenyl tetracarboxylic dianhydride, 40 to 90 mole %        2,2′-bis(trifluoromethyl)benzidine, and 10 to 60 mole %        4,4′-oxydianiline;    -   b. a first imaged copper layer    -   c. a first electrically insulating layer having a first side and        a second side; the first side of the first electrically        insulating layer is next to the first imaged copper layer and is        derived from 100 mole % 3,3′,4,4′-biphenyl tetracarboxylic        dianhydride, 40 to 90 mole % 2,2′-bis(trifluoromethyl)benzidine,        and 10 to 60 mole % 4,4′-oxydianiline;    -   d. a second imaged copper layer; the second side of the first        electrically insulating layer is next to the second imaged        copper layer,    -   e. a polyimide bondply derived from 100 mole %        3,3′,4,4′-biphenyl tetracarboxylic dianhydride, 40 to 90 mole %        2,2′-bis(trifluoromethyl)benzidine, and 10 to 60 mole %        4,4′-oxydianiline;    -   f. a third imaged copper layer;    -   g. a second electrically insulating layer having a first side        and a second side; the first side of the second electrically        insulating layer is next to the third imaged copper layer and is        derived from 100 mole % 3,3′,4,4′-biphenyl tetracarboxylic        dianhydride, 40 to 90 mole % 2,2′-bis(trifluoromethyl)benzidine,        and 10 to 60 mole % 4,4′-oxydianiline    -   h. a fourth imaged copper layer; the second side of the second        electrically insulating layer is next to the fourth imaged        copper layer    -   i. a second polyimide coverlay derived from 100 mole %        3,3′,4,4′-biphenyl tetracarboxylic dianhydride, 40 to 90 mole %        2,2′-bis(trifluoromethyl)benzidine, and 10 to 60 mole %        4,4′-oxydianiline. The polyimide bondply is in direct contact        with the second imaged copper layer and exposed areas of the        second side of the first electrically insulating layer; and in        direct contact with the third imaged copper layer and exposed        areas of the first side of the second electrically insulating        layer. The polyimide bondply has a peel strength from 1 to 2        N/mm as measured in accordance with IPC-TM-650-2.4.9d, when    -   i) the first imaged copper layer, the first electrically        insulating layer and the second imaged copper layer;    -   ii) the polyimide bondply;    -   iii) the third imaged copper layer, the second electrically        insulating layer and the fourth imaged copper layer are        laminated at a lamination temperature from 320 to 380° C. and a        pressure from 150 psi (10.55 Kg/cm) to 400 psi (28.13 Kg/cm).        The first polyimide coverlay is in direct contact with the first        imaged copper layer and exposed areas of the first side of the        first electrically insulating layer and wherein the second        polyimide coverlay is in direct contact with the fourth imaged        copper layer and exposed areas of the second side of the second        electrically insulating layer and wherein the first polyimide        coverlay, the second polyimide coverlay or both comprise a low        conductivity carbon black and a matting agent.

In yet another embodiment, the circuit board, comprising in thefollowing order

-   -   a. a first polyimide coverlay derived from 100 mole %        3,3′,4,4′-biphenyl tetracarboxylic dianhydride, 40 to 90 mole %        2,2′-bis(trifluoromethyl)benzidine, and 10 to 60 mole %        4,4′-oxydianiline;    -   b. a first imaged copper layer    -   c. a first electrically insulating layer having a first side and        a second side; the first side of the first electrically        insulating layer is next to the first imaged copper layer and is        derived from 100 mole % 3,3′,4,4′-biphenyl tetracarboxylic        dianhydride, 40 to 90 mole % 2,2′-bis(trifluoromethyl)benzidine,        and 10 to 60 mole % 4,4′-oxydianiline;    -   d. a second imaged copper layer; the second side of the first        electrically insulating layer is next to the second imaged        copper layer    -   e. a polyimide bondply derived from 100 mole %        3,3′,4,4′-biphenyl tetracarboxylic dianhydride, 40 to 90 mole %        2,2′-bis(trifluoromethyl)benzidine, and 10 to 60 mole %        4,4′-oxydianiline;    -   f. a third imaged copper layer;    -   g. a second electrically insulating layer having a first side        and a second side; the first side of the second electrically        insulating layer is next to the third imaged copper layer and is        derived from 100 mole % 3,3′,4,4′-biphenyl tetracarboxylic        dianhydride, 40 to 90 mole % 2,2′-bis(trifluoromethyl)benzidine,        and 10 to 60 mole % 4,4′-oxydianiline    -   h. a fourth imaged copper layer; the second side of the second        electrically insulating layer is next to the fourth imaged        copper layer;    -   i. a second polyimide coverlay derived from 100 mole %        3,3′,4,4′-biphenyl tetracarboxylic dianhydride, 40 to 90 mole %        2,2′-bis(trifluoromethyl)benzidine, and 10 to 60 mole %        4,4′-oxydianiline. The polyimide bondply is in direct contact        with the second imaged copper layer and exposed areas of the        second side of the first electrically insulating layer and in        direct contact with the third imaged copper layer and exposed        areas of the first side of the second electrically insulating        layer. The polyimide bondply has a peel strength from 1 to 2        N/mm as measured in accordance with IPC-TM-650-2.4.9d, when    -   i) the first imaged copper layer, the first electrically        insulating layer and the second imaged copper layer;    -   ii) the polyimide bondply;    -   iii) the third imaged copper layer, the second electrically        insulating layer and the fourth imaged copper layer are        laminated at a lamination temperature from 320 to 380° C. and a        pressure from 150 psi (10.55 Kg/cm) to 400 psi (28.13 Kg/cm).        The first polyimide coverlay is in direct contact with the first        imaged copper layer and exposed areas of the first side of the        first electrically insulating layer and wherein the second        polyimide coverlay is in direct contact with the fourth imaged        copper layer and exposed areas of the second side of the second        electrically insulating layer and wherein the first polyimide        coverlay, the second polyimide coverlay or both comprise a        pigment and a matting agent and wherein the pigment and the        matting agent are both a low conductivity carbon black and the        low conductivity carbon black is present in the first polyimide        coverlay, the second polyimide coverlay or both in an amount        from 2 to 20 weight percent.

A circuit board in accordance with any of the above embodiments whereinthe first polyimide coverlay, the first electrically insulating layer,the polyimide bondply, the second electrically insulating layer and thesecond polyimide coverlay are derived from 100 mole % 3,3′,4,4′-biphenyltetracarboxylic dianhydride, 20 to 90 mole %2,2′-bis(trifluoromethyl)benzidine, and 10 to 80 mole %4,4′-oxydianiline.

A circuit board in accordance with any of the above embodiments whereinthe first polyimide coverlay, the polyimide bondply and the secondpolyimide coverlay are derived from 100 mole % 3,3′,4,4′-biphenyltetracarboxylic dianhydride, 20 to 90 mole %2,2′-bis(trifluoromethyl)benzidine, and 10 to 80 mole %4,4′-oxydianiline.

In yet another embodiment, the circuit board, comprising in thefollowing order

-   -   a. a first polyimide coverlay derived from 100 mole %        3,3′,4,4′-biphenyl tetracarboxylic dianhydride, 20 to 90 mole %        2,2′-bis(trifluoromethyl)benzidine, and 10 to 80 mole %        4,4′-oxydianiline;    -   b. a first imaged copper layer    -   c. a first electrically insulating layer having a first side and        a second side; the first side of the first electrically        insulating layer is next to the first imaged copper layer and is        derived from 100 mole % 3,3′,4,4′-biphenyl tetracarboxylic        dianhydride, 20 to 90 mole % 2,2′-bis(trifluoromethyl)benzidine,        and 10 to 80 mole % 4,4′-oxydianiline;    -   d. a second imaged copper layer; the second side of the first        electrically insulating layer is next to the second imaged        copper layer;    -   e. a polyimide bondply derived from 100 mole %        3,3′,4,4′-biphenyl tetracarboxylic dianhydride, 20 to 90 mole %        2,2′-bis(trifluoromethyl)benzidine, and 10 to 80 mole %        4,4′-oxydianiline;    -   f. a third imaged copper layer;    -   g. a second electrically insulating layer having a first side        and a second side; the first side of the second electrically        insulating layer is next to the third imaged copper layer and is        derived from 100 mole % 3,3′,4,4′-biphenyl tetracarboxylic        dianhydride, 20 to 90 mole % 2,2′-bis(trifluoromethyl)benzidine,        and 10 to 80 mole % 4,4′-oxydianiline    -   h. a fourth imaged copper layer; the second side of the second        electrically insulating layer is next to the fourth imaged        copper layer;    -   i. a second polyimide coverlay derived from 100 mole %        3,3′,4,4′-biphenyl tetracarboxylic dianhydride, 20 to 90 mole %        2,2′-bis(trifluoromethyl)benzidine, and 10 to 80 mole %        4,4′-oxydianiline. The polyimide bondply is in direct contact        with the second imaged copper layer and exposed areas of the        second side of the first electrically insulating layer; and in        direct contact with the third imaged copper layer and exposed        areas of the first side of the second electrically insulating        layer. The polyimide bondply has a peel strength from 0.7 to 2        N/mm as measured in accordance with IPC-TM-650-2.4.9d, when    -   i) the first imaged copper layer, the first electrically        insulating layer and the second imaged copper layer;    -   ii) the polyimide bondply;    -   iii) the third imaged copper layer, the second electrically        insulating layer and the fourth imaged copper layer are        laminated at a lamination temperature from 300 to 380° C. and a        pressure from 150 psi (10.55 Kg/cm) to 400 psi (28.13 Kg/cm).        The first polyimide coverlay is in direct contact with the first        imaged copper layer and exposed areas of the first side of the        first electrically insulating layer and wherein the second        polyimide coverlay is in direct contact with the fourth imaged        copper layer and exposed areas of the second side of the second        electrically insulating layer and wherein the first polyimide        coverlay, the second polyimide coverlay or both comprise a        pigment and a matting agent and wherein the matting agent is        polyimide particles.

A circuit board in accordance with any of the above embodiments, whereinthe first polyimide coverlay, the second polyimide coverlay or bothcomprise a low conductivity carbon black and a matting agent wherein thematting agent is polyimide particles.

In some embodiments, the circuit board is made by taking a firstpolyimide coverlay (if present), a double-sided clad (first imaged metallayer, first electrically insulating layer and a second imaged metallayer), bondply, a second double-sided clad (third imaged metal layer,second electrically insulating layer and a fourth imaged metal layer)and a second polyimide coverlay (if present) and laminating atlamination temperature of 320 to 380° C. and a pressure from 150 psi(10.55 Kg/cm) to 400 psi (28.13 Kg/cm) using a vacuum platen press.

EXAMPLES

The materials, methods, and examples herein are illustrative only and,except as specifically stated, are not intended to be limiting.

The glass transition temperatures of the polyimide films of the presentinvention were determined using a TA Instruments 2980 dynamic mechanicalanalyzer. The Tg measurement method used a sampling frequency of about1.0 Hz (an amplitude of about 10.0 μm) and a pre-load force of about0.01 N. A temperature ramp rate of about 5° C. min-1 was used.

The Tg was measured at the peak of the tan δ

Tensile Modulus was determined by ASTM D-882.

Tensile strength was determined by ASTM D-882

Elongation was determined by ASTM D-882

Dielectric Constant was measured as described in ASTM D150, “StandardTest Methods for AC Loss Characteristics and Permittivity (DielectricConstant) of Solid Electrical Insulation”. The composite film dielectricconstant was calculated based on the measured capacitance of the 2.5 cmdiameter capacitors.

In-plane CTE of a polyimide films of the present invention were measuredusing a TA Instruments TMA 2940 thermal mechanical analyzer. Theexpansion of a film was measured between about 50° C. and about 250° C.on a second pass. The expansion was then divided by the temperaturedifference (and sample length) to obtain the CTE in ppm ° C.-1. Thefirst pass was used to remove shrinkage from the sample over the sametemperature range as well as to dry out the sample. As such, the secondpass then provided a CTE value characteristic of the film's inherentproperties (e.g. minus water absorption and the effect water would haveon a film's CTE). This method employed a 0.05 N load force and operatedwithin the above mentioned temperature range ramping temperature at arate of about 10° C. per minute

Moisture absorption was determined by IPC-TM-650, Method 2.6.2.

Peel strength data reported in this application are the average of 8 to12 measurements, consistent with requirement for statistically validdata per IPC-TM650 2.4.8d test method. The copper foil for the peelstrength testing was 35 um thick roll annealed (RA) copper foil withpink treatment available from Somers Corporation.

Example 1 BPDA/TFMB

Example 1 shows that a polyimide derived from 100 mole % BPDA and 100mole % TFMB has a peel strength of at least 1 N/mm when laminated at atemperature of 380° C. or greater.

Within a nitrogen inerted glovebox, 21.472 g (0.067 moles) of2,2′-bis(trifluoromethyl)benzidine (TFMB) and 159 grams ofN,N-dimethylacetamide (DMAc) were charged to a dried 250 milliliterjacketed beaker equipped with mechanical stirrer. The mixture was heatedusing recirculating 45° C. glycol-water for several minutes until thediamine had completely dissolved resulting in a near colorless solution.Next, 19.528 g (0.066 moles) of 3,3′,4,4′-biphenyltetracarboxylicdianhydride (BPDA) was added to the diamine solution contained withinthe reaction vessel. Stirring was continued until all of the solidsdissolved and the reaction formed a polyamic acid solution. The polyamicacid solution was decanted and stored at 0° C. until used for filmcasting.

A polyimide film derived from the above polyamic acid was chemicallyimidized through the use of a catalytic solution. The chemicallyimidized film was prepared by casting the polyamic acid solution onto asupport sheet of DuPont MYLAR® film. The cast polyamic acid solution(and support sheet) was immersed into a catalytic solution comprising a1:1 ratio of acetic anhydride and fl-picoline. A gel film was formed.The gel film was peeled from the support sheet and transferred to arestraining frame (pin frame).

The gel film was then heated using a forced air oven to further imidizethe polymer and remove solvent. The gel film was exposed to thefollowing oven temperatures for about ½ hour at each temperature, 150°C., 250° C., 300° C. and 325° C. The polyimide film was removed from thepin frame and analyzed. The data is shown in Table 1.

Two sheets of the film were laminated between two sheets of 35 um thicktreated copper foil in a vacuum platen press at 350 psi. The peelstrength data was measured per IPC-TM650 2.4.9d test method. The data atdifferent lamination peak temperatures are shown in Table 1.

Examples 2-12 show that a polyimide derived from 100 mole % BPDA, 20 to90 mole % TFMB and 10 to 80 mole % 4,4′-ODA has a peel strength of atleast 1 N/mm when laminated at a temperature of 330° C. or greater

Example 2 BPDA/90 TFMB/10 ODA

Within a nitrogen inerted glovebox, 19.711 g (0.0615 moles) of2,2′-bis(trifluoromethyl)benzidine (TFMB), 1.369 g (0.006 moles)4,4′-oxydianiline, and 159 grams of N,N-dimethylacetamide (DMAc) werecharged to a dried 250 milliliter jacketed beaker equipped withmechanical stirrer. The mixture was heated using recirculating 45° C.glycol-water for several minutes until the diamine had completelydissolved resulting in a near colorless solution. Next, 19.919 g (0.0677moles) of 3,3′,4,4′-biphenyltetracarboxylic dianhydride (BPDA) was addedto the diamine solution contained within the reaction vessel. Stirringwas continued until all of the solids dissolved and the reaction formeda polyamic acid solution. The polyamic acid solution was decanted andstored at 0° C. until used for film casting.

A polyimide film derived from the above polyamic acid was chemicallyimidized through the use of a catalytic solution. The chemicallyimidized film was prepared by casting the polyamic acid solution onto asupport sheet of DuPont MYLAR® film. The cast polyamic acid solution(and support sheet) was immersed into a catalytic solution comprising a1:1 ratio of acetic anhydride and β-picoline. A gel film was formed. Thegel film was peeled from the support sheet and transferred to arestraining frame (pin frame).

The gel film was then heated using a forced air oven to further imidizethe polymer and remove solvent. The gel film was exposed to thefollowing oven temperatures for about ½ hour at each temperature, 150°C., 250° C., 300° C. and 325° C. The polyimide film was removed from thepin frame and analyzed. The data is shown in Table 1.

Two sheets of the film were laminated between two sheets of 35 um thicktreated copper foil in a vacuum platen press at 350 psi. The peelstrength data was measured per IPC-TM650 2.4.9d test method. The data atdifferent lamination peak temperatures are shown in Table 1.

Example 3 BPDA/80 TFMB/20 ODA

Within a nitrogen inerted glovebox, 17.879 g (0.0558 moles) of2,2′-bis(trifluoromethyl)benzidine (TFMB), 2.794 g (0.0139 moles)4,4′-oxydianiline, and 159 grams of N,N-dimethylacetamide (DMAc) werecharged to a dried 250 milliliter jacketed beaker equipped withmechanical stirrer. The mixture was heated using recirculating 45° C.glycol-water for several minutes until the diamine had completelydissolved resulting in a near colorless solution. Next, 20.326 g (0.069moles) of 3,3′,4,4′-biphenyltetracarboxylic dianhydride (BPDA) was addedto the diamine solution contained within the reaction vessel. Stirringwas continued until all of the solids dissolved and the reaction formeda polyamic acid solution. The polyamic acid solution was decanted andstored at 0° C. until used for film casting.

A polyimide film derived from the above polyamic acid was chemicallyimidized through the use of a catalytic solution. The chemicallyimidized film was prepared by casting the polyamic acid solution onto asupport sheet of DuPont MYLAR® film. The cast polyamic acid solution(and support sheet) was immersed into a catalytic solution comprising a1:1 ratio of acetic anhydride and β-picoline. A gel film was formed. Thegel film was peeled from the support sheet and transferred to arestraining frame (pin frame).

The gel film was then heated using a forced air oven to further imidizethe polymer and remove solvent. The gel film was exposed to thefollowing oven temperatures for about ½ hour at each temperature, 150°C., 250° C., 300° C. and 325° C. The film was removed from the pin frameand analyzed. The data is shown in Table 1.

Two sheets of the film were laminated between two sheets of 35 um thicktreated copper foil in a vacuum platen press at 350 psi. The peelstrength data was measured per IPC-TM650 2.4.9d test method. The data atdifferent lamination peak temperatures are shown in Table 1.

Example 4 BPDA/70 TFMB/30 ODA

Within a nitrogen inerted glovebox, 15.971 g (0.0498 moles) of2,2′-bis(trifluoromethyl)benzidine (TFMB), 4.279 g (0.0213 moles)4,4′-oxydianiline, and 159 grams of N,N-dimethylacetamide (DMAc) werecharged to a dried 250 milliliter jacketed beaker equipped withmechanical stirrer. The mixture was heated using recirculating 45° C.glycol-water for several minutes until the diamine had completelydissolved resulting in a near colorless solution. Next, 20.75 g (0.0705moles) of 3,3′,4,4′-biphenyltetracarboxylic dianhydride (BPDA) was addedto the diamine solution contained within the reaction vessel. Stirringwas continued until all of the solids dissolved and the reaction formeda polyamic acid solution. The polyamic acid solution was decanted andstored at 0° C. until used for film casting.

A polyimide film derived from the above polyamic acid was chemicallyimidized through the use of a catalytic solution. The chemicallyimidized film was prepared by casting the polyamic acid solution onto asupport sheet of DuPont MYLAR® film. The cast polyamic acid solution(and support sheet) was immersed into a catalytic solution comprising a1:1 ratio of acetic anhydride and β-picoline. A gel film was formed. Thegel film was peeled from the support sheet and transferred to arestraining frame (pin frame).

The gel film was then heated using a forced air oven to further imidizethe polymer and remove solvent. The gel film was exposed to thefollowing oven temperatures for about ½ hour at each temperature, 150°C., 250° C., 300° C. and 325° C. The polyimide film was removed from thepin frame and analyzed. The data is shown in Table 1.

Two sheets of the film were laminated between two sheets of 35 um thicktreated copper foil in a vacuum platen press at 350 psi. The peelstrength data was measured per IPC-TM650 2.4.9d test method. The data atdifferent lamination peak temperatures are shown in Table 1.

Example 5 BPDA/60 TFMB/40 ODA

Within a nitrogen inerted glovebox, 13.981 g (0.0436 moles) of2,2′-bis(trifluoromethyl)benzidine (TFMB), 5.827 g (0.0291 moles)4,4′-oxydianiline, and 159 grams of N,N-dimethylacetamide (DMAc) werecharged to a dried 250 milliliter jacketed beaker equipped withmechanical stirrer. The mixture was heated using recirculating 45° C.glycol-water for several minutes until the diamine had completelydissolved resulting in a near colorless solution. Next, 21.192 g (0.0720moles) of 3,3′,4,4′-biphenyltetracarboxylic dianhydride (BPDA) was addedto the diamine solution contained within the reaction vessel. Stirringwas continued until all of the solids dissolved and the reaction formeda polyamic acid solution. The polyamic acid solution was decanted andstored at 0° C. until used for film casting.

A polyimide film derived from the above polyamic acid was chemicallyimidized through the use of a catalytic solution. The chemicallyimidized film was prepared by casting the polyamic acid solution onto asupport sheet of DuPont MYLAR® film. The cast polyamic acid solution(and support sheet) was immersed into a catalytic solution comprising a1:1 ratio of acetic anhydride and f-picoline. A gel film was formed. Thegel film was peeled from the support sheet and transferred to arestraining frame (pin frame).

The gel film was then heated using a forced air oven to further imidizethe polymer and remove solvent. The gel film was exposed to thefollowing oven temperatures for about ½ hour at each temperature, 150°C., 250° C., 300° C. and 325° C. The resulting polyimide film wasremoved from the pin frame and analyzed. The data is shown in Table 1.

Two sheets of the film were laminated between two sheets of 35 um thicktreated copper foil in a vacuum platen press at 350 psi. The peelstrength data was measured per IPC-TM650 2.4.9d test method. The data atdifferent lamination peak temperatures are shown in Table 1.

Example 6 BPDA/50 TFMB/50 ODA

Within a nitrogen inerted glovebox, 11.904 g (0.03717 moles) of2,2′-bis(trifluoromethyl)benzidine (TFMB), 7.442 g (0.0371 moles)4,4′-oxydianiline, and 159 grams of N,N-dimethylacetamide (DMAc) werecharged to a dried 250 milliliter jacketed beaker equipped withmechanical stirrer. The mixture was heated using recirculating 45° C.glycol-water for several minutes until the diamine had completelydissolved resulting in a near colorless solution. Next, 21.654 g (0.0736moles) of 3,3′,4,4′-biphenyltetracarboxylic dianhydride (BPDA) was addedto the diamine solution contained within the reaction vessel. Stirringwas continued until all of the solids dissolved and the reaction formeda polyamic acid solution. The polyamic acid solution was decanted andstored at 0° C. until used for film casting.

A polyimide film derived from the above polyamic acid was chemicallyimidized through the use of a catalytic solution. The chemicallyimidized film was prepared by casting the polyamic acid solution onto asupport sheet of DuPont MYLAR® film. The cast polyamic acid solution(and support sheet) was immersed into a catalytic solution comprising a1:1 ratio of acetic anhydride and β-picoline. A gel film was formed. Thegel film was peeled from the support sheet and transferred to arestraining frame (pin frame).

The gel film was then heated using a forced air oven to further imidizethe polymer and remove solvent. The gel film was exposed to thefollowing oven temperatures for about ½ hour at each temperature, 150°C., 250° C., 300° C. and 325° C. The film was removed from the pin frameand analyzed. The data is shown in Table 1.

Two sheets of the film were laminated between two sheets of 35 um thicktreated copper foil in a vacuum platen press at 350 psi. The peelstrength data was measured per IPC-TM650 2.4.9d test method. The data atdifferent lamination peak temperatures are shown in Table 1.

Example 7 BPDA/43 TFMB/57 ODA

Into a dried 50 gallon tank, equipped with nitrogen inlet, threeindependently controlled agitator shafts; a low speed anchor mixer, ahigh speed disk disperser, and a high shear rotor-stator emulsifier, andthermocouple, was placed 10.10 kg (31.54 moles) of2,2′-bis(trifluoromethyl)benzidine (TFMB), 8.37 kg (41.81 moles)4,4′-oxydianiline (ODA), and 159.6 kg of N,N-dimethylacetamide (DMAc).

The mixture was heated and stirred at 35° C. for several minutes untilthe diamines had completely dissolved resulting in a straw coloredsolution. The speeds of the anchor, disperser, and emulsifier areadjusted as needed to ensure efficient mixing and dissolution, withoutexcessively heating the mixture. Next, 21.4 kg (72.84 moles) of3,3′,4,4′-biphenyltetracarboxylic dianhydride (BPDA) was added to thediamine solution within the reaction vessel. Stirring was continueduntil all of the solids dissolved and the reaction formed a polyamicacid solution. The viscosity of the resulting polyamic acid solution wasadjusted by chain extension through an addition of a stoichiometricamount of 6 wt % PMDA solution in DMAc or alternatively an equivalentstoichiometric amount of BPDA solids so that the resulting solution hada viscosity of about 2000 poise. The finished solution is filteredthrough a 20 micron bag filter and vacuum degassed to remove entrainedair. The polyamic acid solution was cooled to approximately −6° C.,acetic anhydride dehydrating agent (0.14 cm³/cm³ polymer solution), theimidization catalyst 3-picoline (0.15 cm³/cm³ polymer solution) weremetered in and mixed, and a film was cast using a slot die, onto a 90°C. hot, rotating drum. The resulting gel film was stripped off the drumand fed into a tenter oven, where it was dried and cured to a solidslevel greater than 98%, using convective and radiant heating.

Two sheets of the film were laminated between two sheets of 35 micronthick treated copper foil in a vacuum platen press at 350 psi. The peelstrength data was measured per IPC-TM650 2.4.9d test method. The data atdifferent lamination peak temperatures are shown in Table 1.

Two more sheets of film were laminated between two sheets of 35 micronthick treated copper foil in a vacuum platen press at 350 psi. Thedimensional stability of these clads were measured per IPC-TM650 2.2.4c.The results are summarized in Table 2.

Example 8 BPDA/50 TFMB/50 ODA

Into a dried 50 gallon tank, equipped with nitrogen inlet, threeindependently controlled agitator shafts; a low speed anchor mixer, ahigh speed disk disperser, and a high shear rotor-stator emulsifier, andthermocouple was placed 11.56 kg (36.12 moles) of2,2′-bis(trifluoromethyl)benzidine (TFMB), 7.23 kg (36.12 moles)4,4′-oxydianiline (ODA), and 159.6 kg of N,N-dimethylacetamide (DMAc).

The mixture was heated and stirred at 35° C. for several minutes untilthe diamines had completely dissolved resulting in a straw coloredsolution. The speeds of the anchor, disperser, and emulsifier areadjusted as needed to ensure efficient mixing and dissolution, withoutexcessively heating the mixture. Next, 21.1 kg (71.73 moles) of3,3′,4,4′-biphenyltetracarboxylic dianhydride (BPDA) was added to thediamine solution within the reaction vessel. Stirring was continueduntil all of the solids dissolved and the reaction formed a polyamicacid solution. The viscosity of the resulting polyamic acid solution wasadjusted by chain extension through an addition of a stoichiometricamount of 6 wt % PMDA solution in DMAc or alternatively an equivalentstoichiometric amount of BPDA solids so that the resulting solution hada viscosity of about 1500 poise. Finally, a small amount of belt releaseagent was added to the polyamic acid solution (which enables the castgreen film to be readily stripped from the casting belt) A thin polymerfilm was produced by extruding the film through a slot die onto a movingstainless steel belt. The belt passes into a convective oven, toevaporate solvent and partially imidizing the polymer, to produce a“green” film. Green film solids (as measured by weight loss upon heatingto 300° C.) was ˜70%. The green film was then stripped off the castingbelt and wound up. The green film was then fed into a tenter oven whereit was dried and cured to a solids level greater than 98%, usingconvective and radiant heating to produce a fully cured polyimide film.During tentering, shrinkage was controlled by constraining the filmalong the edges.

Two sheets of the polyimide film were laminated between two sheets of 35um thick treated copper foil in a vacuum platen press at 200 and 350psi. The peel strength data was measured per IPC-TM650 2.4.9d testmethod. The data at different lamination peak temperatures are shown inTable 1.

Example 9 BPDA/43 TFMB/57 ODA

With the polyamic acid polymer solution prepared as described in example7, a thin film was prepared by casting a portion of the solution onto acopper foil (12 um Mitsui 3EC-M35-HTE ED copper) using a doctor blade.The coated copper foil was then restrained within a clip frame film andheated using a forced air oven to remove the solvent and imidize thepolymer. The film was exposed to the following oven temperatures forabout ½ hour, 150° C., 250° C., and 330° C. The resulting single sidedcopper coated polyimide was then removed from the clip frame and thenlaminated to another sheet of copper foil of the same specification asdescribed above in a vacuum platen press at 350 psi pressure and atemperature of 350° C. The peel strength data was measured per IPC-TM6502.4.9d test method. The data is shown in Table 1.

Example 10 prophetic BPDA/50 TFMB/50 ODA

Into a dried 50 gallon tank, equipped with nitrogen inlet, threeindependently controlled agitator shafts; a low speed anchor mixer, ahigh speed disk disperser, and a high shear rotor-stator emulsifier, andthermocouple is placed 11.56 kg (36.12 moles) of2,2′-bis(trifluoromethyl)benzidine (TFMB), 7.23 kg (36.12 moles)4,4′-oxydianiline (ODA), and 159.6 kg of N,N-dimethylacetamide (DMAc).

The mixture is heated and stirred at 35° C. for several minutes untilthe diamines are completely dissolved resulting in a straw coloredsolution. The speeds of the anchor, disperser, and emulsifier can beadjusted as needed to ensure efficient mixing and dissolution, withoutexcessively heating the mixture. Next, 21.1 kg (71.73 moles) of3,3′,4,4′-biphenyltetracarboxylic dianhydride (BPDA) is added to thediamine solution within the reaction vessel. Stirring is continued untilall of the solids dissolved and the reaction forms a polyamic acidsolution. The viscosity of the resulting polyamic acid solution isadjusted by chain extension through an addition of a stoichiometricamount of 6 wt % PMDA solution in DMAc or alternatively an equivalentstoichiometric amount of BPDA solids so that the resulting solution hasa viscosity of about 2000 poise. The finished solution can be filteredthrough a 20 micron bag filter and vacuum degassed to remove entrainedair. The polyamic acid solution is cooled to approximately −6° C.,acetic anhydride dehydrating agent (0.14 cm³/cm³ polymer solution), theimidization catalyst 3-picoline (0.15 cm³/cm³ polymer solution) ismetered in and mixed, and a film is cast using a slot die, onto a 90° C.hot, rotating drum. The resulting gel film is stripped off the drum andfed into a tenter oven, where it is dried and cured to a solids levelgreater than 98%, using convective and radiant heating.

Two sheets of the film are laminated between two sheets of 35 um thicktreated copper foil in a vacuum platen press at 350 psi. It is expectedthat the laminate would have good peel strength measured per IPC-TM6502.4.9d test method.

Example 11 BPDA/3 TFMB/70ODA

Within a nitrogen inerted glovebox, 7.265 g (0.02268 moles) of2,2′-bis(trifluoromethyl)benzidine (TFMB), 10.598 g (0.0529 moles)4,4′-oxydianiline, and 160 grams of N,N-dimethylacetamide (DMAc) werecharged to a dried 250 milliliter jacketed beaker equipped withmechanical stirrer. The mixture was heated using recirculating 45° C.glycol-water for several minutes until the diamine had completelydissolved resulting in a near colorless solution. Next, 22.137 g (0.0752moles) of 3,3′,4,4′-biphenyltetracarboxylic dianhydride (BPDA) was addedto the diamine solution contained within the reaction vessel. Stirringwas continued until all of the solids dissolved and the reaction formeda polyamic acid solution. The polyamic acid solution was decanted andstored at 0° C. until used for film casting.

A polyimide film derived from the above polyamic acid was chemicallyimidized through the use of a catalytic solution. The chemicallyimidized film was prepared by casting the polyamic acid solution onto asupport sheet of DuPont MYLAR® film. The cast polyamic acid solution(and support sheet) was immersed into a catalytic solution comprising a1:1 ratio of acetic anhydride and β-picoline. A gel film was formed. Thegel film was peeled from the support sheet and transferred to arestraining frame (pin frame).

The gel film was then heated using a forced air oven to further imidizethe polymer and remove solvent. The gel film was exposed to thefollowing oven temperatures for about ½ hour at each temperature, 150°C., 250° C., 300° C. and 325° C. The polyimide film was removed from thepin frame and analyzed. The data is shown in Table 1.

Two sheets of the film were laminated between two sheets of 35 um thicktreated copper foil in a vacuum platen press at 350 psi. The peelstrength data was measured per IPC-TM650 2.4.9d test method. The data atdifferent lamination peak temperatures are shown in Table 1.

Example 12 BPDA/20 TFMB/80 ODA

Within a nitrogen inerted glovebox, 5.358 g (0.0167 moles) of2,2′-bis(trifluoromethyl)benzidine (TFMB), 13.399 g (0.0669 moles)4,4′-oxydianiline, and 172 grams of N,N-dimethylacetamide (DMAc) werecharged to a dried 250 milliliter jacketed beaker equipped withmechanical stirrer. The mixture was heated using recirculating 45° C.glycol-water for several minutes until the diamine had completelydissolved resulting in a near colorless solution. Next, 24.243 g (0.0824moles) of 3,3′,4,4′-biphenyltetracarboxylic dianhydride (BPDA) was addedto the diamine solution contained within the reaction vessel. Stirringwas continued until all of the solids dissolved and the reaction formeda polyamic acid solution. The polyamic acid solution was decanted andstored at 0° C. until used for film casting.

A polyimide film derived from the above polyamic acid was chemicallyimidized through the use of a catalytic solution. The chemicallyimidized film was prepared by casting the polyamic acid solution onto asupport sheet of DuPont MYLAR® film. The cast polyamic acid solution(and support sheet) was immersed into a catalytic solution comprising a1:1 ratio of acetic anhydride and β-picoline. A gel film was formed. Thegel film was peeled from the support sheet and transferred to arestraining frame (pin frame).

The gel film was then heated using a forced air oven to further imidizethe polymer and remove solvent. The gel film was exposed to thefollowing oven temperatures for about ½ hour at each temperature, 150°C., 250° C., 300° C. and 325° C. The polyimide film was removed from thepin frame and analyzed. The data is shown in Table 1.

Two sheets of the film were laminated between two sheets of 35 um thicktreated copper foil in a vacuum platen press at 350 psi. The peelstrength data was measured per IPC-TM650 2.4.9d test method. The data atdifferent lamination peak temperatures are shown in Table 1.

Example 13

Example 13 shows polyimides of the present disclosure have goodconformation over circuitry and are useful as a coverlay.

A sheet of Pyralux® AP flexible copper clad laminate with 18 micronthick copper foil (available from DuPont) was imaged with photoresistand copper etching to created imaged copper foil lines of differentwidths using standard procedures in the flexible printed circuit boardindustry. The polymer created in example 7 (film thickness 32 microns)was laminated over the imaged circuit lines to form a coverlay over theimaged flexible circuit. The polyimide coverlay was laminated in avacuum platen press at 350 psi and 320 C peak lamination temperature.The polyimide coverlay showed very good conformation over the circuitrywith no air voids observed. The polyimide coverlay was able to cover thetop of the circuitry with very little thinning.

Example 14

Example 14 shows polyimides of the present disclosure are have good peelstrength when laminated at a temperature of 320° C.

Two sheets of Pyralux® AP flexible copper clad laminate (available fromDuPont) was imaged with photoresist and copper etching to remove all ofthe copper foil from one side of the Pyralux® AP using processing commonin the flexible printed circuit board industry. The polymer created inexample 7 (50 um thick) was laminated between the between the two imagedPyralux® AP clads where the dielectric surface of the AP clad waslaminated to the polymer film of example 7. The polyimide film waslaminated in a vacuum platen press at 350 psi and 320° C. peaklamination temperature. The peel strength between the AP dielectricsurface and the polyimide film of example 7 was measured perIPC-TM650-2.4.9d. Peels strength of 1.4 N/mm between the AP dielectricand the polyimide film of example 7

Example 15

Example 15 shows polyimides of the present disclosure have goodconformation over circuitry and are useful as a bondply.

Two sheets of Pyralux® AP flexible copper clad laminate with 18 micronthick copper foil (available from DuPont) were imaged with photoresistand copper etching to created imaged copper foil lines of differentwidths using standard procedures in the flexible printed circuit boardindustry. The polymer created in example 7 (film thickness of 100microns) was laminated over the imaged circuit lines of the two imagedAP clads to form a bondply between the two imaged flexible circuits. Thepolyimide bondply was laminated in a vacuum platen press at 350 psi and320 C peak lamination temperature. The polymer bondply showed very goodconformation over the circuitry with no air voids observed. Thepolyimide bondply, was able to separate the circuitry on the two APimaged laminates with very little thinning between the two imagedcircuits.

Example 16

Example 16 shows that good peel strength is achieved with metal alloys.

Two sheets the film made in example 7 above were laminated between twosheets of Inconel® 600 metal alloy foil (25 microns thick), availablefrom Ulrich. The peel strength data was measured per IPC-TM650 2.4.9dtest method. An average peel strength of 1.8 N/mm was measured.

Comparative Example 1 BPDA/ODA

Comparative example 1 shows eliminating TFMB compromises properties,including peel strength.

Within a nitrogen inerted glovebox, 16.702 g (0.0834 moles)4,4′-oxydianiline, and 159 grams of N,N-dimethylacetamide (DMAc) werecharged to a dried 250 milliliter jacketed beaker equipped withmechanical stirrer. The mixture was heated using recirculating 45° C.glycol-water for several minutes until the diamine had completelydissolved resulting in a near colorless solution. Next, 24.298 g(0.08266 moles) of 3,3′,4,4′-biphenyltetracarboxylic dianhydride (BPDA)was added to the diamine solution contained within the reaction vessel.Stirring was continued until all of the solids dissolved and thereaction formed a polyamic acid solution. The polyamic acid solution wasdecanted and stored at 0° C. until used for film casting.

A polyimide film derived from the above polyamic acid was chemicallyimidized through the use of a catalytic solution. The chemicallyimidized film was prepared by casting the polyamic acid solution onto asupport sheet of DuPont MYLAR® film. The cast polyamic acid solution(and support sheet) was immersed into a catalytic solution comprising a1:1 ratio of acetic anhydride and fl-picoline. A gel film was formed.The gel film was peeled from the support sheet and transferred to arestraining frame (pin frame).

The gel film was then heated using a forced air oven to further imidizethe polymer and remove solvent. The gel film was exposed to thefollowing oven temperatures for about ½ hour at each temperature, 150°C., 250° C., 300° C. and 325° C. The resulting polyimide film wasremoved from the pin frame and analyzed. The data is shown in Table 1.

Two sheets of the film were laminated between two sheets of 35 um thicktreated copper foil in a vacuum platen press at 350 psi. The peelstrength data was measured per IPC-TM650 2.4.9d test method. The data atdifferent lamination peak temperatures are shown in Table 1.

Comparative Example 2 54BPDA/46PMDA/ODA

Comparative example 2 shows that even though the film can bethermoformed, it has poor adhesion to copper.

Within a nitrogen inerted glovebox, 18.225 g (0.0910 moles)4,4′-oxydianiline, and 159 grams of N,N-dimethylacetamide (DMAc) werecharged to a dried 250 milliliter jacketed beaker equipped withmechanical stirrer. The mixture was heated using recirculating 45° C.glycol-water for several minutes until the diamine had completelydissolved resulting in a near colorless solution. Next, an admixture of12.052 g (0.0409 moles) of 3,3′,4,4′-biphenyltetracarboxylic dianhydride(BPDA) and 10.723 g (0.0492) pyromellitic dianhydride (PMDA) was addedto the diamine solution contained within the reaction vessel. Stirringwas continued until all of the solids dissolved and the reaction formeda polyamic acid solution. The polyamic acid solution was decanted andstored at 0° C. until used for film casting.

A polyimide film derived from the above polyamic acid was chemicallyimidized through the use of a catalytic solution. The chemicallyimidized film was prepared by casting the polyamic acid solution onto asupport sheet of DuPont MYLAR® film. The cast polyamic acid solution(and support sheet) was immersed into a catalytic solution comprising a1:1 ratio of acetic anhydride and f-picoline. A gel film was formed. Thegel film was peeled from the support sheet and transferred to arestraining frame (pin frame).

The gel film was then heated using a forced air oven to further imidizethe polymer and remove solvent. The gel film was exposed to thefollowing oven temperatures for about ½ hour at each temperature, 150°C., 250° C. 300° C. and 325° C. The resulting polyimide film was removedfrom the pin frame and analyzed. The data is shown in Table 1.

Two sheets of the film were laminated between two sheets of 35 um thicktreated copper foil in a vacuum platen press at 350 psi. The peelstrength data was measured per IPC-TM650 2.4.9d test method. The data atdifferent lamination peak temperatures are shown in Table 1.

Comparative Example 3 PMDA/TFMB

Comparative example 3 shows when BPDA is replaced with PMDA thepolyimide is brittle and has poor peel strength.

Within a nitrogen inerted glovebox, 24.552 g (0.0767 moles) of2,2′-bis(trifluoromethyl)benzidine (TFMB) and 159 grams ofN,N-dimethylacetamide (DMAc) were charged to a dried 250 milliliterjacketed beaker equipped with mechanical stirrer. The mixture was heatedusing recirculating 45° C. glycol-water for several minutes until thediamine had completely dissolved resulting in a near colorless solution.Next, 16.55 g (0.0759 moles) of pyromellitic dianhydride (PMDA) wasadded to the diamine solution contained within the reaction vessel.Stirring was continued until all of the solids dissolved and thereaction formed a polyamic acid solution. The polyamic acis solution wasdecanted and stored at 0° C. until used for film casting.

A polyimide film derived from the above polyamic acid was chemicallyimidized through the use of a catalytic solution. The chemicallyimidized film was prepared by casting the polyamic acid solution onto asupport sheet of DuPont MYLAR® film. The cast polyamic acid solution(and support sheet) was immersed into a catalytic solution comprising a1:1 ratio of acetic anhydride and f-picoline. A gel film was formed. Thegel film was peeled from the support sheet and transferred to arestraining frame (pin frame).

The gel film was then heated using a forced air oven to further imidizethe polymer and remove solvent. The gel film was exposed to thefollowing oven temperatures for about ½ hour, 150° C., 250° C., 300° C.and 325° C. The resulting polyimide film was removed from the pin frameand analyzed. The data is shown in Table 1.

Two sheets of the film were laminated between two sheets of 35 um thicktreated copper foil in a vacuum platen press at 350 psi. The peelstrength data was measured per IPC-TM650 2.4.9d test method. The data atdifferent lamination peak temperatures are shown in Table 1.

Comparative Example 4 BPDA/50mTOL/50ODA

Comparative example 4 shows that replacing TFMB with a chemicallysimilar diamine but with 2,2′-methyl benzidine functionality does notyield equivalent peel strength.

Within a nitrogen inerted glovebox, 8.77 g (0.0413 moles) of2,2′-dimethyl-4,4′-diaminobiphenyl, 8.271 g (0.0413 moles)4,4′-oxydianiline, and 159 grams of N,N-dimethylacetamide (DMAc) werecharged to a dried 250 milliliter jacketed beaker equipped withmechanical stirrer. The mixture was heated using recirculating 45° C.glycol-water for several minutes until the diamine had completelydissolved resulting in a near colorless solution. Next, 24.065 g (0.0818moles) of 3,3′,4,4′-biphenyltetracarboxylic dianhydride (BPDA) was addedto the diamine solution contained within the reaction vessel. Stirringwas continued until all of the solids dissolved and the reaction formeda polyamic acid solution. The polyamic acid solution was decanted andstored at 0° C. until used for film casting.

A polyimide film derived from the above polyamic acid was chemicallyimidized through the use of a catalytic solution. The chemicallyimidized film was prepared by casting the polyamic acid solution onto asupport sheet of DuPont MYLAR® film. The cast polyamic acid solution(and support sheet) was immersed into a catalytic solution comprising a1:1 ratio of acetic anhydride and f-picoline. A gel film was formed. Thegel film was peeled from the support sheet and transferred to arestraining frame (pin frame).

The gel film was then heated using a forced air oven to further imidizethe polymer and remove solvent. The gel film was exposed to thefollowing oven temperatures for about ½ hour at each temperature, 150°C., 250° C., 300° C. and 325° C. The resulting polyimide film wasremoved from the pin frame and analyzed. The data is shown in Table 1.

Two sheets of the film were laminated between two sheets of 35 um thicktreated copper foil in a vacuum platen press at 350 psi. The peelstrength data was measured per IPC-TM650 2.4.9d test method. The data atdifferent lamination peak temperatures are shown in Table 1.

Comparative Example 5 PMDA/80ODPA/RODA

Comparative example 5 has poor mechanical properties.

Into a dried 50 gallon tank, equipped with nitrogen inlet, threeindependently controlled agitator shafts: a low speed anchor mixer, ahigh speed disk disperser, and a high shear rotor-stator emulsifier, andthermocouple was placed 20.02 kg (68.49 moles) of1,3-bis(4-aminophenoxy)benzene (RODA) and 159.6 kg ofN,N-dimethylacetamide (DMAc).

The mixture was heated and stirred at 35° C. for several minutes untilthe diamines had completely dissolved resulting in a straw coloredsolution. The speeds of the anchor, disperser, and emulsifier areadjusted as needed to ensure efficient mixing and dissolution, withoutexcessively heating the mixture. Next, 16.99 kg (54.79 moles) of4,4′-oxydiphthalic anhydride (ODPA) and 2.88 kg (13.21 moles)pyromellitic dianhydride (PMDA) was added to the diamine solution withinthe reaction vessel. Stirring was continued until all of the solidsdissolved and the reaction formed a polyamic acid solution. Theviscosity of the resulting polyamic acid solution was adjusted by chainextension through an addition of a stoichiometric amount of 6 wt % PMDAsolution in DMAc or alternatively an equivalent stoichiometric amount ofBPDA solids so that the resulting solution had a viscosity of about 2000poise. The finished solution is filtered through a 20 micron bag filterand vacuum degassed to remove entrained air. The polyamic acid solutionwas cooled to approximately −6° C., acetic anhydride dehydrating agent(0.14 cm³/cm³ polymer solution), the imidization catalyst 3-picoline(0.15 cm³/cm³ polymer solution) were metered in and mixed, and a filmwas cast using a slot die, onto a 90° C. hot, rotating drum. Theresulting gel film was stripped off the drum and fed into a tenter oven,where it was dried and cured to a solids level greater than 98%, usingconvective and radiant heating.

Two sheets of the film were laminated between two sheets of 35 um thicktreated copper foil in a vacuum platen press at 350 psi. The peelstrength data was measured per IPC-TM650 2.4.9d test method. The data atdifferent lamination peak temperatures are shown in Table 1.

Two more sheets of film were laminated between two sheets of 35 um thicktreated copper foil in a vacuum platen press at 350 psi. The dimensionalstability of these clads were measured per IPC-TM650 2.2.4c. The resultsare summarized in Table 2.

Comparative Example 6 PMDA/ODA

Comparative example 6 has poor peel strength.

Two sheets of Kapton® H film (type 100PFC available from DuPont), apolyimide comprised of pyromellitic dianyhdride (PMDA) and4,4′-oxydianiline (ODA), was obtained from E.I. du Pont de Nemours andCompany were laminated between two sheets of 35 um thick treated copperfoil in a vacuum platen press at 350 psi. The peel strength data wasmeasured per IPC-TM650 2.4.9d test method. The data at differentlamination peak temperatures are shown in Table 1.

Comparative Example 7 60PMDA/40BPDA/40ODA/60PPD

Comparative example 7 has poor peel strength.

Two sheets of Kapton® E film (available from DuPont), a copolyimidecomprised of pyromellitic dianhydride (PMDA),3′,4,4′-biphenyltetracarboxylic dianhydride (BPDA), 4,4′-oxydianiline(ODA), and 1,4-phenylene diamine (PPD), was obtained from E.I. du Pontde Nemours and Company. were laminated between two sheets of 35 um thicktreated copper foil in a vacuum platen press at 350 psi. The peelstrength data was measured per IPC-TM650 2.4.9d test method. The data atdifferent lamination peak temperatures are shown in Table 1.

Examples 17 and 18 show that a polyimide derived from 80-90 mole % BPDA,10 to 20 mole % ODPA and 100 mole % TFMB has a peel of at least 1.3 N/mmwhen laminated at a temperature of 350° C. or greater.

Example 17 90 BPDA/10 ODPA/TFMB

Into a dried 250 mL jacketed beaker equipped with mechanical stirrerwithin an inerted nitrogen glovebox was placed 20.68 g (0.064 moles) of2,2′-bis(trifluoromethyl)benzidine (TFMB) and 156 g ofN,N-dimethylacetamide (DMAc).

The mixture was heated and stirred at 40° C. for several minutes untilthe diamine had completely dissolved resulting in a straw coloredsolution. Next, 16.91 g (0.057 moles) of3,3′,4,4′-biphenyltetracarboxylic dianhydride (BPDA) and 1.41 g (0.006moles) of 4,4′-oxydiphthalic anhydride (ODPA) were added to the diaminesolution within the reaction vessel.

Stirring was continued until all of the solids dissolved and thereaction formed a polyamic acid solution. The viscosity of the resultingpolyamic acid solution was adjusted by chain extension through anaddition of a stoichiometric amount of 6 wt % PMDA solution in DMAc oralternatively an equivalent stoichiometric amount of BPDA solids so thatthe resulting solution had a viscosity of about 2000 poise. The solutionwas decanted and stored at 0° C. until used for film casting.

A polyimide film derived from the above polyamic acid was chemicallyimidized through the use of a catalytic solution. The chemicallyimidized film was prepared by casting the polyamic acid solution onto asheet of DuPont MYLAR® film. The polymer (and support sheet) wasimmersed into a catalytic solution comprising a 1:1 ratio of aceticanhydride and β-picoline. Within minutes (upon partial imidization), agel film was formed. The gel film was peeled from the support sheet andtransferred to a restraining frame (pin frame).

The film was then heated using a forced air oven to further imidize thepolymer and remove solvent. The film was exposed to the following oventemperatures for about ½ hour, 150° C., 250° C., and 330° C. The filmwas removed from the pin frame and analyzed.

Two sheets of the film were laminated between two sheets of 35 um thicktreated copper foil in a vacuum platen press at 350 psi. The peelstrength data was measured per IPC-TM650 2.4.9d test method. The data atdifferent lamination peak temperatures are shown in Table 1.

Example 18 80 BPDA/20 ODPA/TFMB

Into a dried 200 mL jacketed beaker equipped with mechanical stirrerwithin an inerted nitrogen glovebox was placed 20.94 g (0.065 moles) of2,2′-bis(trifluoromethyl)benzidine (TFMB) and 156 g ofN,N-dimethylacetamide (DMAc).

The mixture was heated and stirred at 40° C. for several minutes untilthe diamine had completely dissolved resulting in a straw coloredsolution. Next, 15.20 g (0.051 moles) of3,3′,4,4′-biphenyltetracarboxylic dianhydride (BPDA) and 2.85 g (0.013moles) of 4,4′-oxydiphthalic anhydride (ODPA) were added to the diaminesolution within the reaction vessel.

Stirring was continued until all of the solids dissolved and thereaction formed a polyamic acid solution. The viscosity of the resultingpolyamic acid solution was adjusted by chain extension through anaddition of a stoichiometric amount of 6 wt % PMDA solution in DMAc oralternatively an equivalent stoichiometric amount of BPDA solids so thatthe resulting solution had a viscosity of about 2000 poise. The solutionwas decanted and stored at 0° C. until used for film casting.

A polyimide film derived from the above polyamic acid was chemicallyimidized through the use of a catalytic solution. The chemicallyimidized film was prepared by casting the polyamic acid solution onto asheet of DuPont MYLAR® film. The polymer (and support sheet) wasimmersed into a catalytic solution comprising a 1:1 ratio of aceticanhydride and 6-picoline. Within minutes (upon partial imidization), agel film was formed. The gel film was peeled from the support sheet andtransferred to a restraining frame (pin frame).

The film was then heated using a forced air oven to further imidize thepolymer and remove solvent. The film was exposed to the following oventemperatures for about ½ hour, 150° C., 250° C., and 330° C. The filmwas removed from the pin frame and analyzed.

Two sheets of the film were laminated between two sheets of 35 um thicktreated copper foil in a vacuum platen press at 350 psi. The peelstrength data was measured per IPC-TM650 2.4.9d test method. The data atdifferent lamination peak temperatures are shown in Table 1.

Comparative Example 8 60 BPDA/40 ODPA/TFMB

Comparative example 8 shows a film could not me made for testing when 40mole percent of ODPA is used.

Within a nitrogen inerted glovebox, 23.912 g (0.0746 moles) of2,2′-bis(trifluoromethyl)benzidine (TFMB) and 179 grams ofN,N-dimethylacetamide (DMAc) were charged to a dried 250 milliliterjacketed beaker equipped with mechanical stirrer. The mixture was heatedusing recirculating 45° C. glycol-water for several minutes until thediamine had completely dissolved resulting in a near colorless solution.Next, 13.18 g (0.045 moles) of 3,3′,4,4′-biphenyltetracarboxylicdianhydride (BPDA) and 9.03 g (0.029 moles) 4,4′-oxydiphthalic anhydride(ODPA) was added to the diamine solution as an admixture containedwithin the reaction vessel. Stirring was continued until all of thesolids dissolved and the reaction formed a polyamic acid solution. Thepolyamic acid solution was decanted and stored at 0° C. until used forfilm casting.

A polyimide film derived from the above polyamic acid was chemicallyimidized through the use of a catalytic solution. The chemicallyimidized film was prepared by casting the polyamic acid solution onto asupport sheet of DuPont MYLAR® film. The cast polyamic acid solution(and support sheet) was immersed into a catalytic solution comprising a1:1 ratio of acetic anhydride and f-picoline. A gel film was formed. Thegel film was peeled from the support sheet and transferred to arestraining frame (pin frame).

The gel film was then heated using a forced air oven to further imidizethe polymer and remove solvent. The gel film was exposed to thefollowing oven temperatures for about ½ hour at each temperature, 150°C., 250° C., 300° C. and 325° C. A viable polyimide film to conducttesting on could not be obtained using this procedure due extremewrinkling, curl, and tear-out from the restraining frame after cure.

Comparative Example 9 BPDA/10 TFMB/90 ODA

Comparative example 9 shows when 10 mole percent of TFMB is used thepeel strength is low when laminated at 350 degrees C.

Within a nitrogen inerted glovebox, 2.675 g (0.00835 moles) of2,2′-bis(trifluoromethyl)benzidine (TFMB), 15.049 g (0.071 moles)4,4′-oxydianiline, and 168 grams of N,N-dimethylacetamide (DMAc) werecharged to a dried 250 milliliter jacketed beaker equipped withmechanical stirrer. The mixture was heated using recirculating 45° C.glycol-water for several minutes until the diamine had completelydissolved resulting in a near colorless solution. Next, 24.27 g (0.083moles) of 3,3′,4,4′-biphenyltetracarboxylic dianhydride (BPDA) was addedto the diamine solution contained within the reaction vessel. Stirringwas continued until all of the solids dissolved and the reaction formeda polyamic acid solution. The polyamic acid solution was decanted andstored at 0° C. until used for film casting.

A polyimide film derived from the above polyamic acid was chemicallyimidized through the use of a catalytic solution. The chemicallyimidized film was prepared by casting the polyamic acid solution onto asupport sheet of DuPont MYLAR® film. The cast polyamic acid solution(and support sheet) was immersed into a catalytic solution comprising a1:1 ratio of acetic anhydride and β-picoline. A gel film was formed. Thegel film was peeled from the support sheet and transferred to arestraining frame (pin frame).

The gel film was then heated using a forced air oven to further imidizethe polymer and remove solvent. The gel film was exposed to thefollowing oven temperatures for about ½ hour at each temperature, 150°C., 250° C., 300° C. and 325° C. The polyimide film was removed from thepin frame and analyzed. The data is shown in Table 1.

Two sheets of the film were laminated between two sheets of 35 um thicktreated copper foil in a vacuum platen press at 350 psi. The peelstrength data was measured per IPC-TM650 2.4.9d test method. The data atdifferent lamination peak temperatures are shown in Table 1.

Note that not all of the activities described above in the generaldescription or the examples are required, that a portion of a specificactivity may not be required, and that further activities may beperformed in addition to those described. Still further, the order inwhich each of the activities are listed are not necessarily the order inwhich they are performed. After reading this specification, skilledartisans will be capable of determining what activities can be used fortheir specific needs or desires.

In the foregoing specification, the invention has been described withreference to specific embodiments. However, one of ordinary skill in theart appreciates that various modifications and changes can be madewithout departing from the scope of the invention as set forth in theclaims below. All features disclosed in this specification may bereplaced by alliterative features serving the same, equivalent orsimilar purpose. Accordingly, the specification is to be regarded in anillustrative rather than a restrictive sense and all such modificationsare intended to be included within the scope of the invention.

Benefits, other advantages, and solutions to problems have beendescribed above with regard to specific embodiments. However, thebenefits, advantages, solutions to problems, and any element(s) that maycause any benefit, advantage, or solution to occur or become morepronounced are not to be construed as a critical, required, or essentialfeature or element of any or all the claims.

TABLE 1 MD CTE MD MD Tg [tan [50- Tensile Tensile MD EXAMPLE # delta]250° C.] Modulus Strength Elongation 1 BPDA//TFMB 347 11 1289 47 30 2BPDA//90 TFMB/10 ODA 308.6 9.1 724 32.4 52.2 3 BPDA//80 TFMB/20 ODA 32315.3 716 37.8 72.7 4 BPDA//70 TFMB/30 ODA 314 15 728 42.73 110.5 5BPDA//60 TFMB/40 ODA 295.6 15.9 665 38 106 6 BPDA//50 TFMB/50 ODA 288.112.6 663 35.5 105 7 BPDA//43 TFMB/57 ODA 8 BPDA//50 TFMB/50 ODA 350 psi200 psi 9 BPDA//43 TFMB/57 ODA 10 BPDA//50 TFMB/50 ODA 11 BPDA//30TFMB/70 ODA 12 BPDA//20 TFMB/80 ODA Comp 1 BPDA//ODA 292 31 377 24.9 80Comp 2 54BPDA/46PMDA//ODA 314 41 425 29 120 Comp 3 PMDA//TFMB 400 −141600 72 25 Comp 4 BPDA//50mTOL/50ODA 313 26 687 39 66 Comp 520PMDA/80ODPA//RODA 236 >100 516 16.8 71.8 Comp 6 PMDA//ODA Comp 760PMDA/40BPDA// 40ODA/60PPD 17 90BPDA/10ODPA//TFMB 332.2 10.14 780 39.765.1 18 80BPDA/20ODPA//TFMB 321 3.14 720 38.7 60.9 Comp 860BPDA/40ODPA//TFMB Could not be made in to a film for testing Comp 9BPDA//10 TFMB/90 ODA Average Average Average Average Dielectric peelstrength peel strength peel strength peel strength Water Constant at330° C. at 350° C. at 380° C. at 395° C. EXAMPLE # uptake @ 1 kHz (N/mm)(N/mm) (N/mm) (N/mm) 1 0.38 2.77 0.1 1.1 1.4 2 0.42 3.14 1.1 1.6 3 0.733.1 1.6 1.9 4 0.844 2.1 2.0 5 0.92 2.0 2.2 6 1 3.28 2.0 7 1.9 at 320° C.2.7 2.1 8 3.3 3.3 9 2.5 10 11 2.5 3.2 12 1.1 3.2 Comp 1 1.4 3.45 0.2 0.7Comp 2 1.5 3.3 0.2 0.6 Comp 3 1.59 3.37 0 <0.1 Comp 4 3.2 3.24 0.2 0.7Comp 5 0.62 3.43 1.6 Comp 6 <0.1 Comp 7 <0.1 17 0.74 3.04 0.5 1.4 180.74 2.98 0.9 1.3 Comp 8 Comp 9 0.7 1.6

TABLE 2 MD TD MD TD EXAMPLE Etched Etched Thermal Thermal 7 BPDA//43TFMB/ −0.125 −0.081 −0.208 −0.183 57 ODA Comp 20PMDA/ −0.505 −0.506−0.588 −0.583 5 80ODPA//RODA

What is claimed is:
 1. A polyimide metal clad laminate comprising: a. ametal foil; b. a polyimide layer having a first side and a second side,the first side in direct contact with the metal foil, the polyimidelayer comprising: a polyimide derived from 100 mole % 3,3′,4,4′-biphenyltetracarboxylic dianhydride, 20 to 90 mole %2,2′-bis(trifluoromethyl)benzidine, and 10 to 80 mole %4,4′-oxydianiline; wherein the polyimide metal clad laminate does nothave an adhesive layer between the metal foil and the polyimide layer;and wherein the polyimide metal clad laminate has a peel strength offrom 1 to 3.3 N/mm, as measured in accordance with IPC-TM-650-2.4.9d,when the metal foil and the polyimide layer are laminated together at atemperature from 320 to 380° C. and a pressure from 150 psi (10.55Kg/cm) to 400 psi (28.13 Kg/cm).
 2. The polyimide metal clad laminate ofclaim 1 wherein the metal foil is copper.
 3. The polyimide metal cladlaminate of claim 1 wherein the metal foil is copper and the polyimidelayer comprises from 1 to 55 weight percent of a thermally conductivefiller, dielectric fillers or mixtures thereof.
 4. The polyimide metalclad laminate of claim 1 further comprising a second metal foil indirect contact with the second side of the polyimide layer and whereinthe polyimide metal clad laminate does not have an adhesive layerbetween the second metal foil and the polyimide layer.
 5. The polyimidemetal clad laminate of claim 3 wherein the second metal foil is copper.6. The polyimide metal clad laminate of claim 3 wherein the metal foiland the second metal foil are copper and the polyimide layer comprisesfrom 1 to 55 weight percent of a thermally conductive filler, dielectricfillers or mixtures thereof.
 7. The polyimide metal clad laminate ofclaim 3 wherein the polyimide layer comprises a polyimide derived from100 mole % 3,3′,4,4′-biphenyl tetracarboxylic dianhydride, 40 to 90 mole% 2,2′-bis(trifluoromethyl)benzidine, and 10 to 60 mole %4,4′-oxydianiline.
 8. The polyimide metal clad laminate of claim 3wherein the polyimide layer comprises a polyimide derived from 100 mole% 3,3′,4,4′-biphenyl tetracarboxylic dianhydride, 20 to 30 mole %2,2′-bis(trifluoromethyl)benzidine, and 70 to 80 mole %4,4′-oxydianiline.
 9. The polyimide metal clad laminate of claim 1wherein the polyimide layer is from 2 to 26 micron thick.
 10. Thepolyimide metal clad laminate of claim 1 wherein the polyimide layer isfrom 27 to 105 micron thick.
 11. The polyimide metal clad laminate ofclaim 1 wherein the polyimide layer comprises from 1 to 55 weightpercent of a thermally conductive filler, dielectric fillers or mixturesthereof.
 12. The polyimide metal clad laminate of claim 1 wherein thepolyimide layer comprises a polyimide derived from 100 mole %3,3′,4,4′-biphenyl tetracarboxylic dianhydride, 40 to 90 mole %2,2′-bis(trifluoromethyl)benzidine, and 10 to 60 mole %4,4′-oxydianiline.
 13. The polyimide metal clad laminate of claim 1wherein the polyimide layer comprises a polyimide derived from 100 mole% 3,3′,4,4′-biphenyl tetracarboxylic dianhydride, 20 to 30 mole %2,2′-bis(trifluoromethyl)benzidine, and 70 to 80 mole %4,4′-oxydianiline.